Bratiichuk, N. S., et al. “Volodymyr Semenovych Korolyuk (the 80th Anniversary of His Birth)”. Ukrains’kyi Matematychnyi Zhurnal, vol. 57, no. 9, Sept. 2005, pp. 1155-7, https://umj.imath.kiev.ua/index.php/umj/article/view/3674.