Berezansky, Y. M., V. I. Gorbachuk, M. L. Gorbachuk, A. G. Kostyuchenko, S. A. Kuzhel’, V. O. Marchenko, A. M. Samoilenko, Y. S. Samoilenko, and E. Y. Khruslov. “Leonid Pavlovych Nyzhnyk (on His 70-Th Birthday)”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 57, no. 8, Aug. 2005, pp. 1120-2, https://umj.imath.kiev.ua/index.php/umj/article/view/3669.