conf/pods/88 Raghu Ramakrishnan Catriel Beeri Ravi Krishnamurthy Optimizing Existential Datalog Queries. 89-102 1988 PODS db/conf/pods/pods88.html#RamakrishnanBK88 http://doi.acm.org/10.1145/308386.308420 journals/anthology/cd1-3:PODS88/P089.PDF journals/anthology/dvd1:text/1-3/PODS88/P089.PDF conf/pods/AfratiPPRSU86 conf/popl/AhoU79 conf/pods/BancilhonMSU86 conf/sigmod/BancilhonR86 ... conf/pods/BeeriR87 ... books/aw/HopcroftU79 books/sp/Lloyd84 conf/vldb/Mendelzon85 conf/pods/RamakrishnanBS87 conf/pods/Shmueli87 journals/tods/Ullman85 conf/eds/Zaniolo86