COMBINATORY SPACES VERSUS OPERATIVE SPACES WITH STORAGE OPERATION. Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, [S. l.], v. 100, p. 123–142, 2011. Disponível em: https://annual.uni-sofia.bg/index.php/fmi/article/view/250. Acesso em: 14 dec. 2025.