A Flexible Querying Framework (FQF): Some Implementation Issues. - Bert Callens; Guy De Tré; Jörg Verstraete; Axel Hallez (ISCIS, 2003)

Ranking the Possible Alternatives in Flexible Querying: An Extended Possibilistic Approach. - Guy De Tré; Tom Matthé; Koen Tourné; Bert Callens (ISCIS, 2003)

Flexible Querying Techniques Based on CBR. - Guy De Tré; Marysa Demoor; Bert Callens; Lise Gosseye (Handbook of Research on Fuzzy Information Processing in Databases, 2008)