1. Cardinality of D-classes in Bn;Brandon;Semigroup Forum,1972
2. The algebraic theory of semigroups;Clifford,1961
3. Transformations and transformation semigroups;Denes,1976
4. A Moore-Penrose inverse for Boolean relation matrices;Kim;Proc. Second Australian Conf. on Combinatorial Math.,1973
5. Combinatorial properties of binary semigroups;Kim;Period Math. Hungar.,1974