Zarichnyi, M., L. Bazylevych, I. Oleksiv, and Ya. Prytula. “Ivan Pesin (to His 90th Anniversary)”. Matematychni Studii 53, no. 2 (June 24, 2020): 221-224. Accessed December 26, 2024. http://matstud.org.ua/ojs/index.php/matstud/article/view/62.