Mohammad GhasemZadeh Volker Klotz Christoph Meinel Embedding Memoization to the Semantic Tree Search for Deciding QBFs. 681-693 http://springerlink.metapress.com/openurl.asp?genre=article&issn=0302-9743&volume=3339&spage=681 2004 conf/ausai/2004 Australian Conference on Artificial Intelligence db/conf/ausai/ausai2004.html#GhasemZadehKM04