[1] C. Birkhoff:
On the Structure of Abstract Algebras. Proc. Cambridge Phil. Soc. 31 (1935) 433-454.
Zbl 0013.00105
[3] S. Burris H. P. Sankappanavar:
A Course in Universal Algebra. Springer-Verlag, New York-Heidelberg-Berlin 1981.
MR 0648287
[4] A. H. Clifford:
Semigroups Admitting Relative Inverses. Annales of Mathematics, vol.42, No.4, 1941.
MR 0005744 |
Zbl 0063.00920
[14] J. Plonka:
On Varieties of Algebras Defined by Identities of Some Speical Forms. Houston Journal of Mathematics, 14 (1988), 253-263.
MR 0978732
[16] J. Pionka: Biregular and Uniform Identities in Bisemilattices. Demonstratio Mathematica, Vol. XX, No 1-2, 1987, 95- 108.
[17] J. Plonka:
On the Sum of a System of Disjoint Unary Algebra Corresponding to a Given Type. Bull. Acad. Polish. Sc., Vol. XXX, No 7-8, 1982.
MR 0707740
[18] A. Tarski:
Equational Logic and Equational Theories of Algebras in Contributions to Mathematical Logic. Colloquium, Hannover, 1966, Nort-Holland, Amsterdam, 1968, 275-288.
MR 0237410