N. Niu, and S. Easterbrook. RE '08: Proceedings of the 2008 16th IEEE International Requirements Engineering Conference, page 155--164. Washington, DC, USA, IEEE Computer Society, (2008)
S. Liaskos, A. Lapouchnian, Y. Wang, Y. Yu, and S. Easterbrook. Proceedings of the 13th IEEE International Conference on Requirements Engineering (RE'05), page 9--18. Paris, France, IEEE Computer Society, (September 2005)