B. Kuijpers, J. Paredaens, и J. den Bussche. Proc. of 6th International Conference on Database Theory (ICDT 1997), 1186, стр. 432--446. Delphi, Greece, (1997)
B. Kuijpers, J. Paredaens, и L. Vandeurzen. Semantics in Databases, Selected Papers from a Workshop, 1358, стр. 114--135. Prague, Czech Republic, (1995)
B. Kuijpers, J. Paredaens, и J. den Bussche. Proc. of the Workshop on Finite Model Theory and its Applications at FLoC 1999, eds. Michael Benedikt, Leonid Libkin, Jouku Vaananen, Trento (Italy), (1999)