1. G. Birkhoff,On the structure of abstract algebras, Proc. Cambr. Philos. Soc.31 (1935), 433–454.
2. J. Dudek andE. Graczyńska,The lattice of varieties of algebras, Bull. Pol. Acad. Sci.: Math.29, No. 7–8 (1981), 337–340.
3. E. Graczyńska,On regular and symmetric identities (abstract), Bulletin of the section of Logic10, No. 3 (1981), 104–107.
4. G. Grätzer, Universal Algebra, Springer Verlag, Berlin (1979).
5. H. Lakser, R. Padmanabhan andC. R. Platt,Regular identities and finite basis property, Notices. Amer. Math. Soc.21 (1974), 74T-A220.