Pelen , N. N. “On the Dynamics of the Impulsive Predator-Prey Systems With Beddington – DeAngelis Type Functional Response”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 73, no. 4, Apr. 2021, pp. 523 -43, doi:10.37863/umzh.v73i4.619.