G. Grau, C. Cares, X. Franch, and F. Navarrete. International Conference on Software Engineering and Knowledge Engineering, San Francisco, CA, USA, (July 2006)
R. Darimont, and A. v. van Lamsweerde. SIGSOFT '96: Proceedings of the 4th ACM SIGSOFT symposium on Foundations of software engineering, 21, page 179--190. New York, NY, USA, ACM Press, (November 1996)