1. Ada 95 Reference Manual: Language and Standard Libraries: International Standard Iso/Iec 8652:1995(E). In: Taft, S.T., Duff, R.A. (Eds.), Springer LNCS 1246. Berlin, 1997; see also http://www.adahome.com/rm95/
2. Bielak, R., McKim, J.C., 1993. The many faces of a class: views and contracts. In: Proceedings of the TOOLS USA '93, Santa Barbara, CA, Prentice-Hall, New York, pp. 153–161
3. Object oriented design with applications;Booch,1991
4. Campbell, R., Islam, N., Johnson, R., Kougiouris, P., Madany, P., 1991. Choices, frameworks and refinement. In: Proceedings of the International Workshop on Object-Orientation in Operating Systems, Palo alto, CA
5. Introducing object orientation into large and complex systems;Deubler;IEEE Trans. Software Eng.,1994