VOSviewer Nees Jan van Eck and Ludo Waltman VOSviewer -cluster_colors http://www.cwts.nl/projects/epsrc/cluster_colors.txt -label_size_variation 0.35 -map http://www.cwts.nl/projects/epsrc/EPSRC-MixF2-chemistry_medicinal_2006_2010_term_citation_impact_map.csv