Bazarbayevich, M. K., and M. B. Kamildjanovich. “Use of Elements of Predicate Algebra in Solving Proof Problems”. Central Asian Journal of Theoretical and Applied Science, Vol. 2, no. 8, Aug. 2021, pp. 31-34, https://cajotas.casjournal.org/index.php/CAJOTAS/article/view/219.