Dorogovtsev, A.A. (2002) “Mykola Ivanovych Portenko (On His 60th Birthday)”, Ukrains’kyi Matematychnyi Zhurnal, 54(2), pp. 147–148. Available at: https://umj.imath.kiev.ua/index.php/umj/article/view/4050 (Accessed: 5 December 2025).