PETRENYUK, A. Ya. Concerning the demonstration of one theorem of Grunbaum . Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 23, n. 2, p. 268–269, 1971. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/8513. Acesso em: 5 dec. 2025.