1. A. P. Ershov and A. A. Lyapunov, ?On the formalization of the concept of program,? Kibernetika, No. 5 (1967).
2. L. A. Kaluzhnin, ?On the algorithmization of mathematical problems,? Problems of Cybernetics [in Russian], No. 2, Moscow (1959).
3. S. S. Lavrov, ?On memory economy in closed operator schemes,? Zh. Vychisl. Matem. i Matem. Fiz.,1, No. 4 (1961).
4. V. V. Martynyuk, ?On economical memory allocation,? Zh. Vychisl. Matem. i Matem. Fiz.,2, No. 3 (1962).
5. A. P. Ershov, ?Reduction of the memory allocation problem in programming to the problem of coloring the nodes of graphs,? Dokl. Akad. Nauk SSSR,142, No. 4 (1962).