SAFARYAN, R. G. $R-D$-Systems and Irzhina’s branching processes. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 43, n. 2, p. 162–167, 2025. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/9351. Acesso em: 17 feb. 2026.