1. Almuallim H., Akiba Y., & Kaneda S.: An efficient algorithm for finding optimal gain-ratio multiple-split tests on hierarchical attributes in decision tree learning. Proc. of the Nat. Conf. on Artificial Intelligence (AAAI’96) (1996) 703–708
2. Cleverdon C.: Optimizing convenient online access to bibliographic databases. Information Services and Use. 4 (1984) 37–47
3. D’Alessio S., Murray K., Schiaffino R., & Kershenbau A.: The effect of using hierarchical classifiers in text categorization. Proc. of the 6th Int. Conf. on “Recherche d’Information Assistée par Ordinateur”. (RIAO) (2000) 302–313
4. Dumais S. & Chen H.: Hierarchical classification of Web document. Proc. of the 23rd ACM Int. Conf. on Research and Development in Information Retrieval (SIGIR’00) (2000) 256–263
5. Lecture Notes in Artificial Intelligence;F. Esposito,2000