On bounded truth-table and positive degrees. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [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: 11 jan. 2026.