Alavi, Yousef (ed.) et al., Graph theory, combinatorics, and applications, Vol. 1. Proceedings of the sixth quadrennial international conference on the theory and applications of graphs held at Western Michigan University, Kalamazoo, Michigan, May 30-June 3, 1988. New York: John Wiley & Sons Ltd. Wiley-Interscience Publication. 55-75 (1991).
Alavi, Yousef (ed.) et al., Graph theory, combinatorics, and applications, Vol. 2. Proceedings of the sixth quadrennial international conference on the theory and applications of graphs held at Western Michigan University, Kalamazoo, MI, USA, May 30-June 3, 1988. New York: John Wiley & Sons, Inc. Wiley-Interscience Publication. 841-848 (1991).
Alavi, Yousef (ed.) et al., Graph theory, combinatorics, and applications, Vol. 2. Proceedings of the sixth quadrennial international conference on the theory and applications of graphs held at Western Michigan University, Kalamazoo, MI, USA, May 30-June 3, 1988. New York: John Wiley & Sons, Inc. Wiley-Interscience Publication. 705-723 (1991).
Bouchon-Meunier, Bernadette (ed.) et al., Uncertainty in knowledge bases. 3rd international conference on information processing and management of uncertainty in knowlege-based systems, IPMU ’90. Paris, France, July 2-6, 1990. Proceedings. Berlin etc.: Springer-Verlag. Lect. Notes Comput. Sci. 521, 193-202 (1991).