N. Chinchor. Proceedings of the Seventh Message Understanding Conference (MUC-7), page 21 pages. Fairfax, VA, (April 1998)version 3.5, http://www.itl.nist.gov/iaui/894.02/related\_projects/muc/.
J. Bardram. GROUP '97: Proceedings of the international ACM SIGGROUP conference on Supporting group work, page 251-260. New York, NY, ACM Press, (1997)