Boukoucha, Rachid. “EXPLICIT FORM FOR THE FIRST INTEGRAL AND LIMIT CYCLES OF A CLASS OF PLANAR KOLMOGOROV SYSTEMS”. Proceedings of the YSU A: Physical and Mathematical Sciences, vol. 55, no. 1 (254), May 2021, pp. 1-11, doi:10.46991/PYSU:A/2021.55.1.01.