Gösta Grahne Nicolas Spyratos Daniel Stamate Semantics and Containment with Internal and External Conjunctions. 71-82 ICDT1997/P071.pdf 1997 ICDT db/conf/icdt/icdt97.html#GrahneSS97 conf/icdt/97 http://dx.doi.org/10.1007/3-540-62222-5_37 books/aw/AbiteboulHV95 ... conf/stoc/ChandraM77 conf/pods/ChaudhuriV93 conf/pods/Fagin96 journals/jlp/Fitting91 journals/jlp/Fitting93 ... journals/tods/IoannidisR95 journals/jacm/SagivY80 journals/tcs/Stockmeyer76