MARKOV, S. On two interval-arithmetic structures and their properties. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 87, p. 129–164, 1995. Disponível em: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/410. Acesso em: 11 apr. 2025.