T. Leckner, M. Koch, M. Lacher, and R. Stegmann. Proc. Intl. Conf. on Enterprise Information Systems (ICEIS2003), 4, page 259-264. Angers, Frankreich, (April 2003)
M. Nieke, C. Seidl, and S. Schuster. Proceedings of the Tenth International Workshop on Variability Modelling of Software-intensive Systems, page 73--80. New York, NY, USA, ACM, (2016)