Dr Ronald Rousseau is Researcher at The Katholieke Universiteit Leuven, Belgium in the Department of Industrial Sciences and Technology. Rousseau; with Leo Egghe, received the Derek de Solla Price award on scientometrics (2001). He is the former president of the International Society for Scientometrics and Informetrics, and co-author of Introduction to Informetrics, also published by Elsevier. Leo Egghe is the founding Editor in Chief of the Elsevier Journal, Journal of Informetrics. Along with Ronald Rousseau, he received the Derek de Solla Price award on scientometrics (2001) and was in 2014 among highly cited scientists according to Thomson Reuters/Clarivate Analytics. Raf Guns is a researcher at the University of Antwerp in Belgium. He received the 2013 Emerald/EFMD Outstanding Doctoral Research Award for his doctoral dissertation: ‘Missing links: Predicting interactions based on a multi-relational network structure with applications in informetrics’.