Hidetoshi Monoi Yukihiro Morita Hidenori Itoh Toshiaki Takewaki Hiroshi Sakai Shigeki Shibayama Unification-Based Query Language for Relational Knowledge Bases and Its Parallel Execution. 896-903 1988 FGCS db/conf/fgcs/fgcs88.html#MonoiMITSS88