An external characterization of the prime computability. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 83, n. 1, p. 89–111, 1992. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/489. Acesso em: 17 mar. 2026.