1. Center for Studies of Information Resources, School of Information Management, Wuhan University, P.R. China; Center for Science, Technology & Education Assessment (CSTEA), Wuhan University, P.R. China
2. Center for Studies of Information Resources, School of Information Management, Wuhan University, P.R. China; Center for Science, Technology & Education Assessment (CSTEA), Wuhan University, P.R. China; Centre for R&D Monitoring (ECOOM) and Department of MSI, KU Leuven, Belgium
3. Department of Computer Science, ETH Zurich, Switzerland
4. UNU-MERIT, Maastricht University, The Netherlands