1. Bailin, S.C., An Object-Oriented Requirements Specification Method, in CACM, vol 32, no 5, pp 608–623, 1989 May.
2. Brachman, R.J., A Structural Paradigm for Representing Knowledge, Report 3605, BBN, 1978 May.
3. Coad, P. & E. Yourdon, Object-Oriented Analysis, Yourdon Press, Prentice-Hall, 1990.
4. de Champeaux, D., & W. Olthoff, Towards an Object-Oriented Analysis Method, 7th Annual Pacific Northwest Software Quality Conference, pp 323–338, Portland OR, 1989.
5. Goguen, J., Thatcher, J.W., Wagner, E.G., Wright, J.B., Initial Algebra Semantics and Continuous Algebras, JACM, vol 24, no 1, pp 68–75, 1977.