Noboru Takagi Hiroaki Kikuchi Masao Mukaidono Applications of Fuzzy Logic Functions to Knowledge Discovery in Databases. 107-128 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3135&spage=107 2004 journals/trs/2004-2 T. Rough Sets db/journals/trs/trs2.html#TakagiKM04