Samoilenko , A. M., Klesov , O. I., Zaderei, P. V., Nefedova , G. D., Zaderei , N. M. and Gaidei , V. O. (2020) “Nina Opanasivna Virchenko (on his 90th birthday)”, Ukrains’kyi Matematychnyi Zhurnal, 72(8), pp. 1149-1152. doi: 10.37863/umzh.v72i8.6213.