- ECHT. 1990.
- ECHT. 1990.
- Antoine Rizk, Norbert A. Streitz, J. André, editors, Hypertext: Concepts, Systems and Applications, Proceedings of the European Conference on Hypertext, INRIA, France, November 1990. The Cambridge Series on Electronic Publishing, Cambridge University Press, 1990.
- ECHT. 1990.
- ECHT. 1990.