FRYDA, Jan. Some natural axiom system of the plane Euclidean geometry. Annales Mathematicae Silesianae, [S. l.], v. 5, p. 94–98, 1991. Disponível em: https://trrest.vot.pl/ojsus/index.php/AMSIL/article/view/14287. Acesso em: 5 jul. 2025.