M. Lux, and G. Dösinger. International Journal of Knowledge and Learning (IJKL), 3 (4/5):
515-528(2007)ISSN (Online): 1741-1017
ISSN (Print): 1741-1009.
E. Michlmayr, and S. Cazer. Tagging and Metadata for Social Information Organization Workshop in conjunction with the 16th International World Wide Web Conference, (May 2007)