1. Lect Notes Comput Sci;F. L. Bauer,1985
2. G. Booch, J. Rumbaugh, and I. Jacobson. The Unified Modelling Language User Guide. Addison Wesley Longman, Reading, Massachusetts, 1998
3. M. Broy, C. Facchi, R. Grosu, R. Hettler, H. Hussmann, D. Nazareth, F. Regens-burger, O. Slotosch, K. Stoelen. The Requirement Design Specification Language. An Informal Introduction, Part 1. Spectrum. TUM-I9312. TU Munich. 1993
4. M. Broy, C. Facchi, R. Grosu, R. Hettler, H. Hussmann, D. Nazareth, F. Regens-burger, O. Slotosch, K. Stoelen. The Requirement Design Specification Language. An Informal Introduction, Part 2. Spectrum, TUM-I9312, TU Munich, 1993
5. S. Cook and J. Daniels, Designing Object Systems, object-oriented modelling with Syntropy, Prentice Hall, 1994