1. Abrial, J.-R.: The B-Book: Assigning programs to meanings. Cambridge University Press, Cambridge (1996)
2. Broy, M., Stølen, K.: Specification and Development of Interactive Systems. Springer, Heidelberg (2001)
3. Chaochen, Z., Hoare, C.A.R., Ravn, A.P.: A calculus of durations. Information Processing Letters 40, 269–271 (1991)
4. Jackson, M.A.: Problem analysis and structure. In: Hoare, T., Broy, M., Steinbruggen, R. (eds.) Engineering Theories of Software Construction Proceedings of the NATO Summer School, Marktoberdorf. IOS Press, Amsterdam (August 2000)
5. Jackson, M.A.: Problem Frames: Analyzing and structuring software development problems. Addison-Wesley, Reading (2001)