Aghasian, M. M. “THE DENOTATIONAL SEMANTICS OF PROCEDURAL PROGRAMS (the Solution to the Problem of variables’ Number Minimization)”. Proceedings of the YSU A: Physical and Mathematical Sciences, vol. 36, no. 3 (199), Sept. 2002, pp. 23-30, https://doi.org/10.46991/PYSUA.2002.36.3.023.