LEIVA-MALDONADO, Wilfredo. Stationary sunspot equilibrium a survey. Pro Mathematica, [S. l.], v. 10, n. 19-20, p. 201–211, 1996. Disponível em: https://revistas.pucp.edu.pe/index.php/promathematica/article/view/6081. Acesso em: 28 dic. 2025.