1. Lecture Notes in Computer Science;F. Puntigam,1997
2. Puntigam, F.: Concurrent Object-Oriented Programming with Process Types. Der Andere Verlag, Osnabrück (2000)
3. Puntigam, F.: Client and server synchronization expressed in types. In: Proceedings of the OOPSLA 2005 Workshop on Synchronization and Concurrency in Object-Oriented Languages (SCOOL), San Diego, USA (2005)
4. Liskov, B., Wing, J.M.: Specifications and their use in defining subtypes. ACM SIGPLAN Notices 28, 16–28 (1993); Proceedings OOPSLA 1993
5. Lecture Notes in Computer Science;P. Wegner,1988