RALF - A Relation-Algebraic Formula Manipulation System and Proof Checker. - Claudia Hattensperger; Rudolf Berghammer; Gunther Schmidt 001 (AMAST, 1993)

Heterogeneous Relation Algebra. - Gunther Schmidt 001; Claudia Hattensperger; Michael Winter 001 (Relational Methods in Computer Science, 1997)

Rechnergestütztes Beweisen in heterogenen Relationenalgebren. - Claudia Hattensperger (Diss.-Verlag NG-Kopierladen, 1998)

Towards a Formal Framework for Heterogeneous Relation Algebra. - Claudia Hattensperger; Peter Kempf (Inf. Sci., 1999)