DITCHEV, A. On bounded truth-table and positive degrees. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 86, n. 1, p. 61–71, 1994. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/438. Acesso em: 13 apr. 2025.