Reiner Hähnle

Martin Giese, Reiner Hähnle, Daniel Larsson: Rule-Based Simplification of OCL Constraints, OCL and Model Driven Engineering, 2004, (BibTeX entry).
Thomas Baar, Reiner Hähnle, Theo Sattler, Peter H. Schmitt: Entwurfsmustergesteuerte Erzeugung von OCL-Constraints, 2000, (BibTeX entry).
Thomas Baar, Reiner Hähnle: An Integrated Metamodel for OCL Types, 2000, (BibTeX entry).
Reiner Hähnle, Aarne Ranta: Connecting OCL with the Rest of the World, 2001, (BibTeX entry).

dblp: Computer Science Bibliography (University of Trier, Germany). (Note that this does not always work due to different naming schemes.)