1. Post E. L., “The two-valued iterative systems of mathematical logic,” Ann. Math. Stud., no. 5, 1–122 (1942).
2. Yanov Yu. I. and Muchnik A. A., “On the existence of k-valued closed classes without a finite basis,” Dokl. Akad. Nauk SSSR, vol. 127, no. 1, 144–146 (1959).
3. Bulatov M. V., “Finite sublattices in the lattice of clones,” Algebra and Logic, vol. 34, no. 4, 287–306 (1994).
4. Rosenberg I. G., “Über die funktionale Vollstandigkeit in dem mehrvertigen Logiken von mehrren Verandlichen auf endlichen Mengen,” Rozpravy Cs. Akademie Ved., Ser. Math. Nat. Sci., vol. 80, 3–93 (1970).
5. Marchenkov S. S., “On closed classes of self-dual functions of multivalued logics,” in: Problems of Cybernetics. Vol. 36 [Russian], Nauka, Moscow, 1979, 5–22.