Ludo Waltman
Scientific Director / Professor Quantitative Science studies
- Name
- Prof.dr. L.R. Waltman
- Telephone
- +31 71 527 5806
- waltmanlr@cwts.leidenuniv.nl
- ORCID iD
- 0000-0001-8249-1752
Ludo Waltman is professor of Quantitative Science Studies and scientific director at the Centre for Science and Technology Studies (CWTS) at Leiden University. He is a coordinator of the Information & Openness focal area and a member of the Evaluation & Culture focal area. Ludo is co-chair of the Research on Research Institute (RoRI).
Ludo Waltman is professor of Quantitative Science Studies and scientific director at the Centre for Science and Technology Studies (CWTS) at Leiden University. He is a coordinator of the Information & Openness focal area and a member of the Evaluation & Culture focal area. Ludo is co-chair of the Research on Research Institute (RoRI).
Ludo’s work focuses on studying and developing infrastructures, algorithms, and tools to support research assessment, science policy, and scholarly communication. Ludo is open science ambassador of Leiden University, member of the board of ASAPbio, chair of the advisory board of OpenCitations, and coordinator of the Initiative for Open Abstracts (I4OA). Together with his colleague Nees Jan van Eck, Ludo has developed the well-known VOSviewer software for bibliometric visualization. Ludo is coordinator of the CWTS Leiden Ranking, a bibliometric ranking of major universities worldwide. In addition, Ludo served as Founding Editor-in-Chief of the journal Quantitative Science Studies.
Scientific Director / Professor Quantitative Science studies
- Faculteit der Sociale Wetenschappen
- CWTS
- Bascur J., Verberne S., Eck N. van & Waltman L. (2023), Academic information retrieval using citation clusters: in-depth evaluation based on systematic reviews, Scientometrics 128: 2895-2921.
- Abramo G., Aguillo I.F., Aksnes D.W., Boyack K., BurrellQL., Campanario J.M., Chinchilla-Rodríguez Z., Costas Comesana R., D’Angelo C.A., Harzing A., Jamali H.R., Larivière V., Leydesdorff L., Luwel M., Martin B., Mayr P., McCain K.W., Peters I., Rafols I., Robinson-Garcia N., Schubert T., Small H., Sugimoto C.R., Thelwall M., Besselaar P. van den, Leeuwen T.N/ van & Waltman L.R. (2022), Retraction of predatory publishing in Scopus: =evidence on cross-country differences lacks justification, Scientometrics 128(2): 1459-1461.
- Lamers W.S., Boyack K., Larivière V., Sugimoto C.R., Eck N.J.P. van, Waltman L.R. & Murray D. (19 January 2022), A first step in quantifying disagreement across science. Leiden Madtrics. [blog entry].
- Mugabushaka A.M., Eck N.J. van & Waltman L. (2022), Funding COVID-19 research: insights from an exploratory analysis using open data infrastructures, Quantitative Science Studies 3(3): 560-582.
- Eck N.J. van & Waltman L. (2022), Crossref as a source of open bibliographic metadata. MetaArXiv. [working paper].
- Lamers W.S., Boyack K.W., Larivière V.G., Sugimoto C.R., Eck N.J.P. van, Waltman L.R. & Murray D.S. (19 January 2022), A first step in quantifying disagreement across science. Leiden Madtrics. Leiden: Leiden University. [blog entry].
- Mugabushaka A.-M., Eck N.J.P. van & Waltman L.R (25 February 2022), Funding Covid-19 research: insights from an open data infrastructure. Upstream. [blog entry].
- Eck N.J.P. van & Waltman L.R. (6 July 2022), The growth of open peer review. Leiden Madtrics . Leiden: Leiden University. [blog entry].
- Colavizza G., Costas Comesana R., Traag V.A., Eck N.J.P. van, Leeuwen T.N. van & Waltman L.R. (2021), A scientometric overview of CORD-19, PLoS ONE 16(1): e0244839.
- Lamers W.S., Boyack K., Larivière V., Sugimoto C.R., Eck N.J.P. van, Waltman L.R. & Murray D. (2021), Meta-Research: investigating disagreement in the scientific literature, eLife 10: e72737.
- Visser M.S., Eck N.J.P. van & Waltman L.R. (2021), Large-scale comparison of bibliographic data sources: Scopus, Web of Science, Dimensions, Crossref, and Microsoft Academic, Quantitative Science Studies 2(1): 20-41.
- Eck N.J.P. van & Waltman L.R. (2021), Crossref as a source of open bibliographic metadata. In: Glänzel W., Heeffer S., Chi P.-S. & Rousseau R. (Eds.) Proceedings of the 18th international conference of the international society for scientometrics and informetrics.. 1169-1174.
- Waltman L.R., Pinfield S., Kaltenbrunner W. & Woods H.B. (11 March 2021), Peer review in transition?. Open Access Scholarly Publishing Association. [blog entry].
- Waaijers L.J.M., Waltman L.R., Vries S.C.J. de, Leeuwen T.N. van & Eck N.J.P van (2 March 2021), Bona Fide Journals: creating a predatory-free academic publishing environment. Leiden Madtrics. [blog entry].
- Rijcke S. de, Waltman L.R. & Leeuwen T.N van (19 May 2021), Halt the h-index. Halt the h-index. Leiden University: Leiden Madtrics. [blog entry].
- Eck N.J. van & Waltman L.R. (22 July 2021), VOSviewer goes online! (Part 2). Leiden Madtrics. [blog entry].
- Eck N.J. van & Waltman L.R. (16 July 2021), VOSviewer goes online! (Part 1). Leiden Madtrics. [blog entry].
- Subelj L., Waltman L., Traag V. & Eck N.J. van (2020), Intermediacy of publications, Royal Society Open Science 7(1): 190207.
- Waltman L., Boyack K.W., Colavizza G. & Eck N.J. van (2020), A principled methodology for comparing relatedness measures for clustering publications, Quantitative Science Studies 1(2): 691-713.
- Bascur Cifuentes J.P., Verberne S., Eck N.J.P. & Waltman L.R. (2020), Browsing citation clusters for academic literature search: a simulation study with systematic reviews. Cabanac G., Frommholz I. & Mayr P. (Eds.), Proceedings of the 10th International Workshop on Bibliometric-enhanced Information Retrieval. 10th International Workshop on Bibliometric-enhanced Information Retrieval co-located with 42nd European Conference on Information Retrieval (ECIR 2020) 14 April 2020 - 14 April 2020 no. 2591: CEUR-WS.org. 53-65.
- Traag V.A., Waltman L. & Van Eck N.J. (2019), From Louvain to Leiden: guaranteeing well-connected communities, Scientific Reports 9: e5233.
- Traag V.A. & Waltman L. (2019), Systematic analysis of agreement between metrics and peer review in the UK REF, Palgrave Communications 5: e29.
- Wouters P.F., Sugimoto C.R., Lariviere V., McVeigh M.E., Pulverer B., De Rijcke S. & Waltman L.R. (2019), Rethinking impact factors: Better ways to judge a journal (comment), Nature 569: 621-623.
- Waltman L. & Van Eck N.J. (2019), Field normalization of scientometric indicators. In: Glänzel W., Moed H.F., Schmoch U. & Thelwall M. (Eds.), Springer Handbook of Science and Technology Indicators. Cham: Springer. 281-300.
- Bascur J.P., Van Eck N.J. & Waltman L. (2019), An interactive visual tool for scientific literature search: Proposal and algorithmic specification. Cabanac G., Frommholz I. & Mayr P. (Eds.), Proceedings of the 8th International Workshop on Bibliometric-enhanced Information Retrieval. 8th International Workshop on Bibliometric-enhanced Information Retrieval 14 April 2019 - 14 April 2019: CEUR Workshop Proceedings. 76-87.
- Murray D., Lamers W., Boyack K.W., Larivière V., Sugimoto C., Van Eck N.J. & Waltman L. (2019), Measuring disagreement in science, Proceedings of the 17th International Conference of the International Society for Scientometrics and Informetrics. 17th International Conference on Scientometrics and Informetrics 2 September 2019 - 5 September 2019 2370-2375.
- Visser M., Van Eck N.J. & Waltman L. (2019), Large-scale comparison of bibliographic data sources: Web of Science, Scopus, Dimensions, and Crossref, Proceedings of the 17th International Conference of the International Society for Scientometrics and Informetrics. 17th International Conference on Scientometrics and Informetrics 2 September 2019 - 5 September 2019 2358-2369.
- Lamers W.S., Van Eck N.J. & Waltman L. (2019), Variations in citation practices across the scientific landscape: Analysis based on a large full-text corpus, Proceedings of the 17th International Conference of the International Society for Scientometrics and Informetrics. 17th International Conference on Scientometrics and Informetrics 2 September 2019 - 5 September 2019 2121-2132.
- Subelj L., Waltman L., Traag V.A. & Van Eck N.J. (2019), Intermediacy of publications, Proceedings of the 17th International Conference of the International Society for Scientometrics and Informetrics. 17th International Conference on Scientometrics and Informetrics 2 September 2019 - 5 September 2019 1288-1300.
- Hagenaars N., Kruif T. de, Laar L. van de, Waltman L., Meijer I., Levi M. & Gupta A. (2019), The relationship between publication volume of biomedical research and burden of disease. Center for Open Science. [working paper].
- Colavizza G., Boyack K.W., Eck N.J. van & Waltman L. (2018), The Closer the Better: Similarity of publication pairs at different co-citation levels, Journal of the Association for Information Science and Technology 69(4): 600-609.
- Boyack K.W., Eck N.J. van, Colavizza G. & Waltman L. (2018), Characterizing in-text citations in scientific articles: A large-scale analysis, Journal of Informetrics 12(1): 59-73.
- Van de Laar L., De Kruif T., Waltman L.R., Meijer I., Gupta A. & Hagenaars N. (2018), Improving the evaluation of worldwide biomedical research output: classification method and standardised bibliometric indicators by disease, BMJ Open 8(6): e020818.
- Eck N.J. van & Waltman L. (2018), Analyzing the activities of visitors of the Leiden Ranking website, Journal of Data and Information Science 3(3): 81-98.
- Van Eck N.J. & Waltman L. (2018), Analyzing the activities of visitors of the Leiden Ranking website, Proceedings of the 23rd International Conference on Science and Technology Indicators. 23rd International Conference on Science and Technology Indicators 12 September 2018 - 14 September 2018. Leiden: 23rd International Conference on Science and Technology Indicators. 857-867.
- Lamers W.S., Eck N.J.P. van, Waltman L.R. & Hoos H.H. (2018), Patterns in citation context: The case of the field of scientometrics, Proceedings of the 23rd International Conference on Science and Technology Indicators. 23rd International Conference on Science and Technology Indicators 12 September 2018 - 14 September 2018 1114-1122.
- Waltman L.R. & Traag V.A. (2017), Impact factors: Is the Nature Index at odds with DORA? (Correspondence), Nature 545(7655): 412-412.
- Van Eck N.J.P. & Waltman L.R. (2017), Citation-based clustering of publications using CitNetExplorer and VOSviewer, Scientometrics 111(2): 1053-1070.
- Boyack K., Glänzel W., Gläser J., Havemann F., Scharnhorst A., Thijs B., Van Eck N.J., Van Velden T. & Waltman L.R. (2017), Topic identification challenge, Scientometrics 111(2): 1223-1224.
- Waltman L. (2017), Special section on performance-based research funding systems. Editorial, Journal of Informetrics 11(3): 904-904.
- Colavizza G., Boyack K.W., Van Eck N.J. & Waltman L. (2017), Exploring the similarity of articles co-cited at different levels. 16th International Conference of the International Society for Scientometrics and Informetrics, Wuhan, Proceedings of the 16th International Conference of the International Society for Scientometrics and Informetrics. 16th International Conference of the International Society for Scientometrics and Informetrics 16 October 2017 - 20 October 2017 549-560.
- Waltman L., Boyack K.W., Colavizza G. & Van Eck N.J. (2017), A principled methodology for comparing relatedness measures for clustering publications. 16th International Conference of the International Society for Scientometrics and Informetrics, Wuhan, Proceedings of the 16th International Conference of the International Society for Scientometrics and Informetrics. 16th International Conference of the International Society for Scientometrics and Informetrics 16 October 2017 - 20 October 2017 691-702.
- Boyack K.W., Van Eck N.J., Colavizza G. & Waltman L. (2017), Reference behavior in the full text of scientific articles: A large-scale analysis, Proceedings of the 16th International Conference of the International Society for Scientometrics and Informetrics. 16th International Conference of the International Society for Scientometrics and Informetrics 16 October 2017 - 20 October 2017 787-798.
- Van Eck N.J. & Waltman L. (2017), Accuracy of citation data in Web of Science and Scopus. 16th International Conference of the International Society for Scientometrics and Informetrics, Wuhan, Proceedings of the 16th International Conference of the International Society for Scientometrics and Informetrics. 16th International Conference of the International Society for Scientometrics and Informetrics 16 October 2017 - 20 October 2017 1087-1092.
- Van Eck N.J. & Waltman L. (2017), Using full-text data to create improved term maps. 16th International Conference of the International Society for Scientometrics and Informetrics, Wuhan, Proceedings of the 16th International Conference of the International Society for Scientometrics and Informetrics. 16th International Conference of the International Society for Scientometrics and Informetrics 16 October 2017 - 20 October 2017 1136-1141.
- Berghmans S., Cousijn H., Deakin G., Meijer I., Mulligan A., Plume A., De Rijcke S., Rushforth A., Tatum C., Van Leeuwen T. & Waltman L. (2017), Open Data: The researcher perspective: CWTS / Elsevier / Universiteit Leiden.
- Chorus C. & Waltman L.R. (2016), A Large-Scale Analysis of Impact Factor Biased Journal Self-Citations, PLoS ONE 11(8): e0161021.
- Waltman L., Van Eck N.J., Visser M. & Wouters P. (2016), The elephant in the room: The problem of quantifying productivity in evaluative scientometrics, Journal of Informetrics 10(2): 671-674.
- Waltman L.R. (2016), A review of the literature on citation impact indicators, Journal of Informetrics 10(2): 365-391.
- Perianes-Rodriguez A., Waltman L. & Van Eck N.J. (2016), Constructing bibliometric networks: A comparison between full and fractional counting, Journal of Informetrics 10(4): 1178-1195.
- Waltman L. & Van Eck N.J.P. (2016), The need for contextualized scientometric analysis: An opinion paper, Proceedings of the 21th International Conference on Science and Technology Indicators. STI Conference, 21st Int. Conf. on Science and Technology Indicators 14 September 2016 - 16 September 2016. Proceedings of the 21th International Conference on Science and Technology Indicators 541-549.
- Subelj L., Van Eck N.J. & Waltman L. (2016), Clustering scientific publications based on citation relations: A systematic comparison of different methods, PLoS ONE 11(4): e0154404.
- Waltman L. (2016), Special section on size-independent indicators in citation analysis. Editorial, Journal of Informetrics 10(2): 645-645.
- Waltman L. (2016), Special section on statistical inference in citation analysis. Editorial, Journal of Informetrics 10(4): 1224-1224.
- Wang Q. & Waltman L.R. (2016), Large-scale analysis of the accuracy of the journal classification systems of Web of Science and Scopus, Journal of Informetrics 10(2): 347-364.
- Waltman Ludo (2016), Conceptual difficulties in the use of statistical inference in citation analysis, Journal of Informetrics 10(4): 1249-1252.
- Ruiz-Castillo J. & Waltman L. (2015), Field-normalized citation impact indicators using algorithmically constructed classification systems of science, Journal of Informetrics 9(1): 102-117.
- Hicks D., Wouters P., Waltman L., De Rijcke S. & Rafols I. (2015), The Leiden Manifesto for research metrics, Nature 520(7548): 429-431.
- De Groot C.J.M., Van Leeuwen T.N., Mol B.J. & Waltman L. (2015), A longitudinal analysis of publications on maternal mortality, Paediatric and Perinatal Epidemiology 29(6): 481-489.
- Waltman L. & Van Eck N.J. (2015), Field-normalized citation impact indicators and the choice of an appropriate counting method, Proceedings of the 15th International Conference of the International Society for Scientometrics and Informetrics. 15th International Conference on Scientometrics and Informetrics (ISSI), 29 Jun-4 July, 2015, Bogazici University, Istanbul (Turkey) 29 June 2015 - 4 July 2015 328-339.
- Waltman L. & Van Eck N.J. (2015), Field-normalized citation impact indicators and the choice of an appropriate counting method, Journal of Informetrics 9(4): 872-894.
- Stegehuis C., Litvak N. & Waltman L.R. (2015), Predicting the long-term citation impact of recent publications, Journal of Informetrics 9(3): 642-657.
- Rodrigues S.P., Van Eck N.J., Waltman L. & Jansen F.W. (2014), Mapping patient safety: A large-scale literature review using bibliometric visualisation techniques, BMJ Open 4(3): e004468.
- Waltman L.R., Van Raan A.F.J. & Smart S. (2014), Exploring the relationship between the engineering and physical sciences and the health and life sciences by advanced bibliometric methods, PLoS ONE 9(10): e111530.
- Van Eck N.J. & Waltman L. (2014), Visualizing bibliometric networks. In: Ding Y., Rousseau R. & Wolfram D. (Eds.), Measuring scholarly impact: Springer International Publishing. 285-320.
- Van Eck N.J.P. & Waltman L. (2014), CitNetExplorer: A new software tool for analyzing and visualizing citation networks, Proceedings of the 19th International Conference on Science and Technology Indicators. 181-192.
- Van Eck N.J.P. & Waltman L. (2014), CitNetExplorer: A new software tool for analyzing and visualizing citation networks no. CWTS-WP-2014-002. Leiden: Centre for Science and Technology Studies.
- Waltman L.R. & Costas Comesana R. (2014), F1000 Recommendations as a potential new data source for research evaluation: a comparison with citations, Journal of the Association for Information Science and Technology 65(3): 433-445.
- Van Eck N.J. & Waltman L. (2014), CitNetExplorer: A new software tool for analyzing and visualizing citation networks, Journal of Informetrics 8(4): 802-823.
- Ahlgren P. & Waltman L. (2014), The correlation between citation-based and expert-based assessments of publication channels: SNIP and SJR vs. Norwegian quality assessments, Journal of Informetrics 8(4): 985-996.
- Waltman L. & Van Eck N.J. (2013), A systematic empirical comparison of different approaches for normalizing citation impact indicators, Journal of Informetrics 7(4): 833-849.
- Waltman L., Van Eck N.J., Van Leeuwen T.N. & Visser M.S. (2013), Some modifications to the SNIP journal impact indicator, Journal of Informetrics 7(2): 272-285.
- Waltman L., Van Eck N.J. & Wouters P. (2013), Counting publications and citations: Is more always better?, Journal of Informetrics 7(3): 635-641.
- Van Eck N.J., Waltman L., Van Raan A.F.J., Klautz R.J.M. & Peul W.C. (2013), Citation analysis may severely underestimate the impact of clinical research as compared to basic research, PLoS ONE 8(4): e62395.
- Waltman L. & Van Eck N.J. (2013), A smart local moving algorithm for large-scale modularity-based community detection, The European Physical Journal B 86(11): e471.
- Costas R., Calero-Medina C., Waltman L. & Wouters P. (2013), The relationship between the performance of editorial board members and the impact of scientific journals : an exploratory analysis, Proceedings of 18Th International Conference on Science and Technology Indicators. 18Th International Conference on Science and Technology Indicators 4 September 2013 - 6 September 2013 87-95.
- Waltman L. & Van Eck N.J. (2013), A systematic empirical comparison of different approaches for normalizing citation impact indicators. 14th International Conference of the International Society for Scientometrics and Informetrics, Vienna , Proceedings of the 14th International Conference of the International Society for Scientometrics and Informetrics. 14th International Conference of the International Society for Scientometrics and Informetrics 15 July 2013 - 19 July 2013 1649-1664.
- Waltman L., Wouters P.F. & Van Eck N.J. (2013), Counting publications and citations: Is more always better? 14th International Conference of the International Society for Scientometrics and Informetrics, Vienna, Proceedings of the 14th International Conference of the International Society for Scientometrics and Informetrics. 14th International Society of Scientometrics and Informetrics Conference 15 July 2013 - 19 July 2013 455-467.
- Waltman L.R. & Van Eck N.J.P. (2013), A systematic empirical comparison of different approaches for normalizing citation impact indicators: Centre for Science and Technology Studies.
- Waltman L.R., Van Eck N.J.P. & Wouters P. (2013), Counting publications and citations: Is more always better?: Centre for Science and Technology Studies.
- Waltman L.R. & Van Eck N.J.P. (2013), A smart local moving algorithm for large-scale modularity-based community detection no. CWTS-WP-2013-005. Leiden: Centre for Science and Technology Studies.
- Waltman L., Van Eck N.J., Dekker R. & Kaymak U. (2013), An evolutionary model of price competition among spatially distributed firms, Computational Economics 42(4): 373-391.
- Waltman L. & Van Eck N.J. (2013), Source normalized indicators of citation impact: an overview of different approaches and an empirical comparison, Scientometrics 96(3): 699-716.
- Waltman L. & Schreiber M. (2013), On the calculation of percentile-based bibliometric indicators, Journal of the American Society for Information Science and Technology 64(2): 372-379.
- Waltman L.R., Van Eck N.J.P. & Raan A.F.J. van (2012), Universality of citation distributions revisited, 63(1): 72-77.
- Waltman L. & Van Eck N.J.P. (2012), Constructing a publication-level classification system of science, Proceedings of the 17th International Conference on Science and Technology Indicators. 803-814.
- Tijssen R.J.W., Waltman L. & Van Eck N.J.P. (2012), Research collaboration and the expanding science grid: Measuring globalization processes worldwide, Proceedings of the 17th International Conference on Science and Technology Indicators. 779-790.
- Waltman L., Calero-Medina C.M., Kosten J., Noyons E.C.M., Tijssen R.J.W., Van Eck N.J., Van Leeuwen T.N., Van Raan A.F.J., Visser M.S. & Wouters P.F. (2012), The Leiden Ranking 2011/2012: Data collection, indicators, and interpretation, Proceedings of the 17th International Conference on Science and Technology Indicators. 791-802.
- Van Eck N.J.P., Waltman L.R., Raan A.F.J. van, Klautz R.J.M. & Peul W.C. (2012), Citation analysis may severely underestimate the impact of clinical research as compared to basic research: Centre for Science and Technology Studies, Leiden University.
- Waltman L.R., Calero Medina C.M., Kosten J., Noyons E.C.M., Tijssen R.J.W., Van Eck N.J.P., Leeuwen T.N. van, Raan A.F.J. van, Visser M.S. & Wouters P. (2012), The Leiden Ranking 2011/2012: Data collection, indicators, and interpretation: Centre for Science and Technology Studies, Leiden University.
- Waltman L.R., Van Eck N.J.P., Van Leeuwen T.N. & Visser M.S. (2012), Some modifications to the SNIP journal impact indicator: Centre for Science and Technology Studies, Leiden University.
- Waltman L.R. & Schreiber M. (2012), On the calculation of percentile-based bibliometric indicators: Centre for Science and Technology Studies, Leiden University.
- Waltman L.R. & Van Eck N.J.P. (2012), Source normalized indicators of citation impact: An overview of different approaches and an empirical comparison: Centre for Science and Technology Studies, Leiden University.
- Waltman L.R. & Van Eck N.J.P. (2012), A new methodology for constructing a publication-level classification system of science: Centre for Science and Technology Studies, Leiden University.
- Waltman L.R. (2012), An empirical analysis of the use of alphabetical authorship in scientific publishing: Centre for Science and Technology Studies, Leiden University.
- Waltman L.R., Costas Comesana R. & Eck N.J.P. van (2012), Some limitations of the h Index: a commentary on Ruscio and colleagues' analysis of bibliometric indices, Measurement: Interdisciplinary Research and Perspectives 10(3): 172-175.
- Waltman L.R., Calero-Medina C.M., Kosten J., Noyons E.C.M., Tijssen R.J.W., Van Eck N.J.P., Leeuwen T.N. van, Raan A.F.J. van, Visser M.S. & Wouters P. (2012), The Leiden Ranking 2011/2012: Data collection, indicators, and interpretation, Journal of the American Society for Information Science and Technology 63(12): 2419-2432.
- Waltman L. & Van Eck N.J. (2012), The Inconsistency of the h-index, Journal of the American Society for Information Science and Technology 63(2): 406-415.
- Waltman L.R. (2012), An empirical analysis of the use of alphabetical authorship in scientific publishing, Journal of Informetrics 6(4): 700-711.
- Waltman L.R. & Van Eck N.J.P. (2012), A new methodology for constructing a publication-level classification system of science, 63(12): 2378-2392.
- Waltman L. & Van Eck N.J.P. (2012), A mathematical analysis of the long-run behavior of genetic algorithms for social modeling, Soft Computing 16(6): 1071-1089.
- Waltman L.R., Van Eck N.J.P., Leeuwen T.N. van, Visser M.S. & Raan A.F.J. van (2011), On the correlation between bibliometric indicators and peer review: Reply to Opthof and Leydesdorff, Scientometrics 88(3): 1017-1022.
- Waltman L.R., Van Eck N.J.P., Leeuwen T.N. van, Visser M.S. & Raan A.F.J. van (2011), Towards a new crown indicator: An empirical analysis, Scientometrics 87(3): 467-481.
- Bornmann L. & Waltman L. (2011), The detection of "hot regions" in the geography of science-A visualization approach by using density maps, Journal of Informetrics 5(4): 547-553.
- Waltman L.R., Eck N.J.P. van, Leeuwen T.N. van, Visser M.S. & Raan A.F.J. van (2011), On the correlation between bibliometric indicators and peer review: reply to Opthof and Leydesdorff, Scientometrics 88: 1017-1022.
- Van Eck N.J.P., Waltman L. & Tijssen R.J.W. (2011), Globalization of science: Geographical distance measurements of research collaboration, Proceedings of the 13th International Conference of the International Society for Scientometrics and Informetrics. . PROCEEDINGS OF ISSI 2011: THE 13TH CONFERENCE OF THE INTERNATIONAL SOCIETY FOR SCIENTOMETRICS AND INFORMETRICS, VOLS 1 AND 2 181-186.
- Waltman L. & Bornmann L. (2011), The detection of "hot regions" in the geography of science - A visualization approach by using density maps. The13th Conference of the International Society for Scientometrics and Informetrics, Proceedings of ISSI 2011: The13th Conference of the International Society for Scientometrics and Informetrics, Vols 1 and 2.. . PROCEEDINGS OF ISSI 2011: THE 13TH CONFERENCE OF THE INTERNATIONAL SOCIETY FOR SCIENTOMETRICS AND INFORMETRICS, VOLS 1 AND 2 1076-1078.
- Van Eck N.J.P., Tijssen R.J.W. & Waltman L. (2011), Globalization of public-private research in worldwide science: co-publication trends and geographical distances between research partners, Proceedings of the 2011 Atlanta Conference on Science and Innovation Policy. .
- Waltman L.R., Van Eck N.J.P. & Raan A.F.J. van (2011), Universality of citation distributions revisited: Centre for Science and Technology Studies, Leiden University.
- Waltman L.R., Tijssen R.J.W. & Van Eck N.J.P. (2011), Globalisation of science in kilometres: Centre for Science and Technology Studies, Leiden University.
- Waltman L.R., Yan E. & Van Eck N.J.P. (2011), A recursive field-normalized bibliometric performance indicator: An application to the field of library and information science: Centre for Science and Technology Studies, Leiden University.
- Waltman L.R. & Van Eck N.J.P. (2011), The inconsistency of the h-index: Centre for Science and Technology Studies (CWTS), Leiden University.
- Waltman L.R., Van Eck N.J.P., Dekker R. & Kaymak U. (2011), An evolutionary model of price competition among spatially distributed firms: Centre for Science and Technology Studies, Leiden University.
- Waltman L.R., Tijssen R.J.W. & Van Eck N.J.P. (2011), Globalisation of science in kilometres, Journal of Informetrics 5(4): 574-582.
- Tijssen Robert J.W., Waltman Ludo & Van Eck Nees Jan (2011), Collaborations span 1,553 kilometres, 473(7346): 154-154.
- Waltman L.R., Van Eck N.J.P. & Yan E. (2011), A recursive field-normalized bibliometric performance indicator: an application to the field of library and information science, Scientometrics 89(1): 301-314.
- Egghe L. & Waltman L. (2011), Relations between the shape of a size-frequency distribution and the shape of a rank-frequency distribution, Information Processing and Management 47(2): 238-245.
- Waltman L.R., Van Eck N.J.P. & Dekker R. (2011), Economic modeling using evolutionary algorithms: the effect of a binary encoding of strategies, Journal of Evolutionary Economics 21(5): 737-756.
- Van Eck N.J.P. & Waltman L. (2011), Text mining and visualization using VOSviewer, ISSI Newsletter 7(3): 50-54.
- Waltman L.R., Van Eck N.J.P., Leeuwen T.N. van, Visser M.S. & Raan A.F.J. van (2011), Towards a new crown indicator: Some theoretical considerations, Journal of Informetrics 5(1): 37-47.
- Waltman L.R. & Van Eck N.J.P. (2010), The relation between Eigenfactor, audience factor, and influence weight, 61(7): 1476-1486.
- Van Eck N.J.P. & Waltman L.R. (2010), Software survey: VOSviewer, a computer program for bibliometric mapping, Scientometrics 84(2): 523-538.
- Raan A.F.J. van, Leeuwen T.N. van, Visser M.S., Van Eck N.J.P. & Waltman L.R. (2010), Rivals for the crown: Reply to Opthof and Leydesdorff. Leiden: SW Centrum Wetensch. & Techn. Studies (CWTS).
- Waltman L.R., Van Eck N.J.P. & Noyons E.C.M. (2010), A unified approach to mapping and clustering of bibliometric networks. Leiden: SW Centrum Wetensch. & Techn. Studies (CWTS).
- Waltman L.R. & Van Eck N.J.P. (2010), The relation between eigenfactor, audience factor, and influence weight. Leiden: SW Centrum Wetensch. & Techn. Studies (CWTS).
- Van Eck N.J.P., Waltman L.R., Dekker R. & Van den Berg J. (2010), A comparison of two techniques for bibliometric mapping: Multidimensional scaling and VOS. Leiden: SW Centrum Wetensch. & Techn. Studies (CWTS).
- Waltman L., Van Eck N.J. & Noyons E.C.M. (2010), A unified approach to mapping and clustering of bibliometric networks, Journal of Informetrics 4(4): 629-635.
- Van Eck N.J., Waltman L., Noyons E.C.M. & Buter R.K. (2010), Automatic term identification for bibliometric mapping, Scientometrics 82(3): 581-596.
- Raan A.F.J. van, Leeuwen T.N. van, Visser M.S., Van Eck N.J.P. & Waltman L.R. (2010), Rivals for the crown: Reply to Opthof and Leydesdorff, Journal of Informetrics 4(3): 431-435.
- Van Eck N.J.P., Waltman L.R., Dekker R. & Berg J. van den (2010), A comparison of two techniques for bibliometric mapping: Multidimensional scaling and VOS, 61(12): 2405-2416.
- Van Eck N.J.P. & Waltman L.R. (2009), How to Normalize Cooccurrence Data? An Analysis of Some Well-Known Similarity Measures, 60(8): 1635-1651.
- Van Eck N.J.P. & Waltman L.R. (2009), On the proper understanding of the limiting behavior of generalizations of the h- and g-indices, Journal of Informetrics 3(4): .
- Van Eck N.J. & Waltman L. (2009), VOSviewer: A computer program for bibliometric mapping. 12th International Conference on Scientometrics and Informetrics, 12th International Conference on Scientometrics and Informetrics. Proceedings, Vol.2. 2. . 14th International Society of Scientometrics and Informetrics Conference (ISSI) 886-897.
- Waltman L. & Van Eck N.J.P. (2009), A Taxonomy of Bibliometric Performance Indicators Based on the Property of Consistency, Proceedings of the 12th International Conference on Scientometrics and Informetrics. . 14th International Society of Scientometrics and Informetrics Conference (ISSI) 1002-1003.
- Van Eck N.J.P. & Waltman L.R. (2009), VOSviewer: A computer program for bibliometric mapping, Proceedings of the 12th International Conference on Scientometrics and Informetrics. 12th International Conference on Scientometrics and Informetrics 14 July 2009 - 17 July 2009.
- Waltman L. & Van Eck N.J.P. (2009), A simple alternative to the h-index, ISSI Newsletter 5(3): 46-48.
- Waltman L.R. & Van Eck N.J.P. (2009), Some comments on Egghe's derivation of the impact factor distribution, Journal of Informetrics 3(4): 363-366.
- Waltman L.R. & Van Eck N.J.P. (2009), Robust Evolutionary Algorithm Design for Socio-Economic Simulation: Some Comments, Computational Economics 33(1): 103-105.
- Van Eck N.J.P. & Waltman L. (2008), Generalizing the h- and g- indices, Journal of Informetrics 2(4): 263-271.
- Waltman L. & Kaymak U. (2008), Q-learning agents in a Cournot oligopoly model, Journal of Economic Dynamics & Control 32(10): 3275-3293.
- Van Eck N.J.P. & Waltman L. (2008), Appropriate similarity measures for author co-citation analysis, Journal of the American Society for Information Science and Technology 59(10): 1653-1661.
- Waltman L. & Van Eck N.J. (2008), Some comments on the journal weighted impact factor proposed by Habibzadeh and Yadollahie, Journal of Informetrics 2(4): 369-372.
- Van Eck N.J.P. & Waltman L. (2007), VOS: A new method for visualizing similarities between objects. In: Decker R. & Lenz H.-J. (Eds.), Studies in Classification, Data Analysis, and Knowledge Organization. Advances in Data Analysis: Springer. 299-306.
- Waltman L. & Kaymak U. (2007), A theoretical analysis of cooperative behaviorin multi-agent Q-learning, Proceedings of the 2007 IEEE International Symposium on Approximate Dynamic Programming and Reinforcement Learning. . 2007 IEEE International Symposium on Approximate Dynamic Programming and Reinforcement Learning 84-91.
- Van Eck N.J.P. & Waltman L. (2007), Bibliometric mapping of the computational intelligence field, International Journal of Uncertainty, Fuzziness and Knowledge-Based Systems 15(5): 625-645.
- Waltman L. & Van Eck N.J.P. (2007), Some comments on the question whether co-occurrence data should be normalized, Journal of the American Society for Information Science and Technology 58(11): 1701-1703.
- Van Eck N.J.P., Waltman L., Berg J. van den & Kaymak U. (2006), Visualizing the WCCI 2006 knowledge domain, Proceedings of the 2006 IEEE International Conference on Fuzzy Systems. . 2006 IEEE INTERNATIONAL CONFERENCE ON FUZZY SYSTEMS, VOLS 1-5 1671-1678.
- Van Eck N.J.P., Waltman L., Berg J. van den & Kaymak U. (2006), Visualizing the computational intelligence field, IEEE Computational Intelligence Magazine 1(4): 6-10.
- Van Eck N.J.P., Waltman L. & Berg J. van den (2005), A novel algorithm for visualizing concept associations, Proceedings of the 16th International Workshop on Database and Expert Systems Applications. . Sixteenth International Workshop on Database and Expert Systems Applications, Proceedings 405-409.
- Waltman L., Kaymak U. & Van den Berg J. (2005), Maximum likelihood parameter estimation in probabilistic fuzzy classifiers, Proceedings of the 2005 IEEE International Conference on Fuzzy Systems. . Proceedings of IEEE International Conference on Fuzzy Systems 2005 1098-1103.
- Berg J. van den, Van Eck N.J.P., Waltman L. & Kaymak U. (2004), A VICORE architecture for intelligent knowledge management, Proceedings of the KDNet Symposium on Knowledge-Based Services for the Public Sector. 63-74.
- President
- Member of the Board of Directors
- Chair of the International Advisory Board for OpenCitations