Bojkova, Elka. “An Example of a Finite Number of Recursively Enumerable $m$-Degrees Containing an Infinite Sequence of Recursively Enumerable Sets”. Ann. Sofia Univ. Fac. Math. and Inf. 87 (December 12, 1995): 223–234. Accessed November 21, 2024. https://ftl5.uni-sofia.bg/index.php/fmi/article/view/415.