K. Okada, F. Maeda, Y. Ichikawaa, и Y. Matsushita. CSCW '94: Proceedings of the 1994 ACM conference on Computer supported cooperative work, стр. 385--393. New York, NY, USA, ACM, (1994)
Y. Ichikawa, K. ichi Okada, G. Jeong, S. Tanaka, и Y. Matsushita. ECSCW'95: Proceedings of the fourth conference on European Conference on Computer-Supported Cooperative Work, стр. 279--292. Norwell, MA, USA, Kluwer Academic Publishers, (1995)