1. Belousov, V.D.,Systems of quasigroups with generalized identities. Usp. Mat. Nauk, 20(121), (1965), 75–146. (Russian)
2. Cohn, P.M.,Universal Algebra. Harper & Row, New York, 1965.
3. Mal'cev, I.A.,Iterative algebras and Post varieties. In: The metamathematics of algebraic systems, North Holland, Amsterdam, 1971, 396–415.
4. Pöschel, R. and L.A. Kalužnin,Funktionen- und Relationenalgebren. VEB DVW, Berlin 1979; Birkhäuser, Basel u. Stuttgart 1979.
5. Reischer, C. and D.A. Simovici,Several
remarks
on
iteration
properties
of
switching
functions. Proc. XII. Int. Symp. Multiple-valued logic, Paris (1982), 244–247.