DITCHEV, A. On the effective enumerations of partial structures. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 83, n. 1, p. 29–37, 1992. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/482. Acesso em: 22 nov. 2024.