db/journals/jacm/BusscheGAG97.html Jan Van den Bussche Dirk Van Gucht Marc Andries Marc Gyssens On the completeness of object-creating database transformation languages. 272-319 1997 44 J. ACM 2 http://doi.acm.org/10.1145/256303.256311 db/journals/jacm/jacm44.html#BusscheGAG97 JACM/44/P0272.pdf