MARKOV, K. A new bound on the absorption coefficient of a two-phase medium. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 94, p. 123–131, 2002. Disponível em: https://admin.uni-sofia.bg/index.php/fmi/article/view/195. Acesso em: 15 jan. 2025.