References
- SEA Bull. Math. v.26 Quasi-regular regressive transformation semigroups Kemprasit, Y.
- Semigroup Forum v.53 Remarks on isomorphisms of regressive transformation semigroups Saito, T.;Aoki, K.;Kajitori, K.
- Proc. Royal Soc. A. v.120 On the semigroups of order-decreasing finite full transformations Umar, A.
- Semigroup Forum v.53 Semigroups of order-decreasing transformations: The isomorphism theorem Umar, A.