Abstract
This study uses two bibliometric methods, direct citation and co-authorship, to investigate the interdisciplinary changes in information sciences during 1978—2007. The disciplines of references and co-authors from five information science journals were analysed. Furthermore, Brillouin’s Index was adopted to measure the degree of interdisciplinarity. The study revealed that information science researchers have cited the publications of library and information science (LIS) most frequently. The co-authors of information science articles are also primarily from the discipline of LIS, but the percentage of references to LIS is much higher. This indicates that information science researchers mainly rely on publications in LIS, and they often produce scientific papers with researchers from LIS. The discipline rankings generated by direct citation and co-authorship show a significant consistency via Spearman’s correlation coefficient test. The interdisciplinary degree of information science has displayed growth. In particular, the degree of interdisciplinarity for co-authors has grown.