ФЕДАК, Іван Васильович. ON TOURNAMENTS OF YUNG MATHEMATICIANS AND UNSOLVED MATHEMATICAL PROBLEMS. PRECARPATHIAN BULLETIN OF THE SHEVCHENKO SCIENTIFIC SOCIETY. Number, [S. l.], n. 1(17), p. 127–130, 2019. Disponível em: https://pvntsh.nung.edu.ua/index.php/number/article/view/239. Acesso em: 6 dec. 2025.