Khadzhiivanov, N., and E. Šchepin. 1995. “Cohomologies of Countable Unions of Closed Sets With Applications to Cantor Manifolds”. Ann. Sofia Univ. Fac. Math. And Inf. 87 (December):249-55. https://ftl5.uni-sofia.bg./index.php/fmi/article/view/418.