Myroniv, I., V. Zhebka, S. Ostapov, and O. Val. “Development of a System for Graphic Captcha Systems Recognition Using Competing Cellular Automata”. Eastern-European Journal of Enterprise Technologies, vol. 6, no. 2 (96), Nov. 2018, pp. 39-44, doi:10.15587/1729-4061.2018.148307.