Parvanova И.; Radulov В. Circumsphere and Insphere of a Polyhedron. Mathematics and Education in Mathematics, [S. l.], v. 54, p. 173–179, 2025. DOI: 10.55630/mem.2025.54.173-179. Disponível em: https://smb.math.bas.bg/mem/index.php/memjournal/article/view/199. Acesso em: 6 oct. 2026.