Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 58, pp. 130?148, 1976.

Constraint Programming, B. (1994) Constraint Programming, B. Mayoh, E. Tougu, J. Penjam (Eds.), NATO Advanced Science Institute Series, Series F: Computer and System Sciences, Vol 131, Springer-Verlag, 1994  

Languages mentioned Gentzen {1994}