Hovhannisyan, A.H., et al. “ON A CONNECTION BETWEEN A CLASS OF SYSTEMS OF ORDINARY DIFFERENTIAL EQUATIONS AND INTEGRAL OPERATORS WITH SEMI-SEPARABLE KERNEL”. Proceedings of the YSU A: Physical and Mathematical Sciences, vol. 52, no. 2 (246), Aug. 2018, pp. 77-83, doi:10.46991/PYSU:A/2018.52.2.077.