1. Almeida, J.: Finite Semigroups and Universal Algebra. World Scientific, Singapore (1994)
2. Auinger, K.: Strict regular *-semigroups. In: Howie, J.M., Munn, W.D., Weinert, H.-J. (eds.) Proceedings of the Conference on Semigroups and Applications, pp. 190–204. World Scientific, Singapore (1992)
3. Benenson, I.E.: On the lattice of quasivarieties of models. Izv. vuzuv. Matematika (12), 14–20 (1979) (Russian); English translation in Soviet Math. (Iz. VUZ) 23(12), 13–21 (1979)
4. Burris, S., Sankappanavar, H.P.: A Course in Universal Algebra. Springer, Heidelberg (1981)
5. Caicedo, X.: Finitely axiomatizable quasivarieties of graphs. Algebra Universalis 34, 314–321 (1995)