1. The Hausdorff–Kuratowski hierarchy of ω-regular languages and a hierarchy of Muller automata;Barua;Theoret. Comput. Sci.,1992
2. Transductions and context free languages;Berstel,1979
3. Adherences of languages;Boasson;J. Comput. Syst. Sci.,1980
4. Weak second order arithmetic and finite automata;Büchi;Z. Math. Logik Grundlag. Math.,1960
5. J.R. Büchi, On a decision method in restricted second order arithmetic, logic methodology and philosophy of science, Proc. 1960 Internat. Congr., Stanford University Press, 1962, pp. 1–11.