1. Milner, R.: Communication and concurrency, (Prentice Hall, New York 1989)
2. Hoare, C.A.R.: Communicating sequential processes, (Prentice Hall, New York 1985)
3. International Standards Organisation‘Informations processing systems — Open Systems Interconnection — LOTOS — A formal description technique based on the temporal ordering of observational behaviour’, ISO 8807, 1989 1989-02-15 edition