On classifying subsets of natural numbers by their computable permutations. Combarro, E.F. (2004) Sibirskij Matematicheskij Zhurnal
On interpretability in theories containing arithmetic Marie Hájková, Petr Hájek (1972) Fundamenta Mathematicae
On recursive measure of classes of recursive sets Antonín Kučera (1982) Commentationes Mathematicae Universitatis Carolinae
On some properties of r -maximal sets and Q 1 - N -reducibility. Omanadze, R. (2002) Georgian Mathematical Journal