T. Green. Proceedings of the fifth conference of the British Computer Society, Human-Computer Interaction Specialist Group on People and computers V, page 443--460. New York, NY, USA, Cambridge University Press, (1989)
D. Moody. Proceedings of Advances in Databases and Information Systems, 8th East European Conference, ADBIS 2004, Budapest, Hungary, September 22-25, page 129-143. Springer, (2004)