S. Matsubara, K. Toyama, and Y. Inagaki. Australian Joint Conference on Artificial Intelligence, volume 1747 of Lecture Notes in Computer Science, page 134-143. Springer, (1999)
X. Tan, T. Hirata, and Y. Inagaki. SIGAL International Symposium on Algorithms, volume 450 of Lecture Notes in Computer Science, page 241-250. Springer, (1990)