M. Fuller, E. Mackie, R. Sacks-Davis, and R. Wilkinson. Proceedings of the 16th Annual International ACM SIGIR Conference on Research and Development in Information Retrieval, page 204-213. ACM Press, (1993)
A. Hotho, S. Staab, and G. Stumme. Knowledge Discovery in Databases: PKDD 2003, 7th European Conference on Principles and Practice of Knowledge Discovery in Databases, Proceedings, volume 2838 of Lecture Notes in Computer Science, page 217-228. Springer, (2003)