DENEVA, S. Private movements of rolling sphere on absolutely rough tore. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 86, n. 2, p. 123–132, 1994. Disponível em: https://admin.uni-sofia.bg/index.php/fmi/article/view/509. Acesso em: 16 jan. 2025.