BEREZANSKY, Y. M.; GORBACHUK, V. I.; GORBACHUK, M. L.; KOSTYUCHENKO, A. G.; KUZHEL’, S. A.; MARCHENKO, V. O.; SAMOILENKO, A. M.; SAMOILENKO, Y. S.; KHRUSLOV, E. Y. Leonid Pavlovych Nyzhnyk (on his 70-th birthday). Ukrains’kyi Matematychnyi Zhurnal, v. 57, n. 8, p. 1120-1122, 25 Aug. 2005.