POGORZELSKI, H. A. Recursive Arithmetic of Skolem. MATHEMATICA SCANDINAVICA, [S. l.], v. 11, p. 33–36, 1962. DOI: 10.7146/math.scand.a-10647. Disponível em: https://www.mscand.dk/article/view/10647. Acesso em: 1 may. 2024.