KOSTIN, A. V. Some generalisation of the shadow problem in the Lobachevsky space. Ukrains’kyi Matematychnyi Zhurnal, [S. l.], v. 73, n. 1, p. 61–68, 2021. DOI: 10.37863/umzh.v73i1.2397. Disponível em: https://umj.imath.kiev.ua/index.php/umj/article/view/2397. Acesso em: 14 apr. 2025.