Noriko Sugimoto Hiroki Ishizaka Takeshi Shinohara An Efficient Derivation for Elementary Formal Systems Based on Partial Unification. 350-364 2001 conf/dis/2001 Discovery Science http://link.springer.de/link/service/series/0558/bibs/2226/22260350.htm db/conf/dis/dis2001.html#SugimotoIS01