Danielian, E.A., and S.K. Arzumanyan. 2011. “STABILITY OF FREQUENCY DISTRIBUTION IN FRAME OF NATURAL PARAMETRIZATION. I”. Proceedings of the YSU A: Physical and Mathematical Sciences 45 (1 (224). Yerevan, Armenia:18-22. https://doi.org/10.46991/PYSU:A/2011.45.1.018.