BerezovskyA. A., SamoilenkoA. M., and KhomchenkoA. N. “Seminar-School ‘Mathematical Simulation’”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 49, no. 8, Aug. 1997, p. 1152, https://umj.imath.kiev.ua/index.php/umj/article/view/5110.