LUCHKA , T. F.; LUCHKA , A. Yu. Development of direct methods of mathematical physics in works by M. P. Kravchuk. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 44, n. 7, p. 931–939, 1992. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8126. Acesso em: 6 dec. 2025.