1. S. Abbas, W. Ashraf and A. H. Shah, On dominions and varieties of bands, Asian Eur. J. Math., 14(8) (2021), Article ID: 2150140.
2. N. Alam, P. M. Higgins and N. M. Khan, Epimorphisms, dominions and Hcommutative semigroups, Semigroup Forum, 100 (2020), 349–363.
3. A. H. Clifford and G. B. Preston, The Algebraic Theory of Semigroups, Mathematical Surveys and Monographs, Vol. 7, No.1. American Mathematical Society (1961, 1967)).
4. J. M. Howie, Fundamentals of semigroup theory, Clarendon Press, Oxford, 1995.
5. J. R. Isbell, Epimorphisms and dominions, In: Proceedings of the conference on Categorical Algebra, La Jolla, (1965), 232–246. Lange and Springer, Berlin (1966).
6. N. M. Khan, Epimorphically closed permutative varieties, Trans. Amer. Math. Soc., 287 (1985), 507–528.
7. N. M. Khan, On saturated permutative varieties and consequences of permutation identities. J. Aust. Math. Soc.(Ser. A), 38(1985), 186–197.
8. A. Nagy, Special Classes of Semigroups, Springer, 2001.