Gergely Tamás; Úry László: Nondeterministic programming within the frame of first order classical logic : part 1. In: Acta cybernetica, (4) 4. pp. 333-354. (1980)
Gergely Tamás; Úry László: Nondeterministic programming within the frame of first order classical logic : part 2. In: Acta cybernetica, (4) 4. pp. 355-375. (1980)