SHELAH, S. . Models of PA: Standard Sytems Without Minimal Ultrafilters. Sarajevo Journal of Mathematics, [S. l.], v. 14, n. 1, p. 3–11, 2018. Disponível em: https://sjm.anubih.ba/index.php/sjm/article/view/80. Acesso em: 15 oct. 2024.