Mykola Ivanovych Shkil’ (on his 80th birthday) - Korolyuk, V. S.; Lukovsky, I. O.; Perestyuk, N. A.; Pratsiovytyi, M. V.; Samoilenko, A. M.; Yakovets, V. P. (Ukrains’kyi Matematychnyi Zhurnal, 2012)