HELFGOTT, Michel. El Dr. Tola y San Marcos. Pro Mathematica, [S. l.], v. 8, n. 15-16, p. 37–39, 1994. Disponível em: https://revistas.pucp.edu.pe/index.php/promathematica/article/view/10173. Acesso em: 28 dic. 2025.