PtashnikB. I. and SamoilenkoA. M. (1998) “All-Ukrainian scientific conference ‘New approaches to the solution of differential equations’”, Ukrains’kyi Matematychnyi Zhurnal, 50(3), pp. 454–455. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/4949 (Accessed: 27July2024).