Johnson-Lenz, Peter; Johnson-Lenz, Trudy (March 1991). "Post-mechanistic groupware primitives: rhythms, boundaries and containers". International Journal of Man-Machine Studies. 34 (3): 395–417. doi:10.1016/0020-7373(91)90027-5.
Aparicio, M and Costa, C. (2012) Collaborative systems: characteristics and features. In Proceedings of the 30th ACM international conference on Design of communication (SIGDOC '12). ACM, New York, NY, USA, 141-146. doi:10.1145/2379057.2379087