DITCHEV, A. SOME RESULTS ON THE UPPER-SEMILATTICE OF R.E. $m$-DEGREES INSIDE A SINGLE R.E. $tt$-DEGREE. Ann. Sofia Univ. Fac. Math. and Inf., [S. l.], v. 96, p. 23–34, 2004. Disponível em: https://ftl5.uni-sofia.bg/index.php/fmi/article/view/158. Acesso em: 23 nov. 2024.