AbdullayevF. G.; SavchukV. V.; SamoilenkoA. M.; SerdyukA. S. International conference on the Mathematical Analysis, Differential Equations, and Their Applications (MADEA-8) devoted to the 80th Birthday of Academician A. M. Samoilenko. Ukr. Mat. Zhurn. 2018, 70, 1439-1440.