Babenko, V. F., A. A. Ligun, and V. P. Motornyi. “On the Results of N. P. Korneichuk Obtained in 1990–1999”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 52, no. 1, Jan. 2000, pp. 5-8, https://umj.imath.kiev.ua/index.php/umj/article/view/4391.