1. Rumbaugh, J.: Relations as semantic constructs in an object-oriented language. In: Procs. of OOPSLA, pp. 466–481 (1987)
2. Pattern Languages of Program Design;J. Noble,2000
3. Lecture Notes in Computer Science;G. Bierman,2005
4. Albano, A., Bergamini, R., Ghelli, G., Orsini, R.: An object data model with roles. In: Procs. of Very Large DataBases (VLDB 1993), pp. 39–51 (1993)
5. Noble, J., Grundy, J.: Explicit relationships in object-oriented development. In: Procs. of TOOLS 18 (1995)