PtashnikB. I. and SamoilenkoA. M. (2002) “International scientific conference "New approaches to the solution of differential equations"”, Ukrains’kyi Matematychnyi Zhurnal, 54(4), pp. 575-576. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/4095 (Accessed: 1September2024).