1. Algebraic Theory of Machines, Languages and Semigroups;Arbib,1968
2. The Algebraic Theory of Semigroups;Clifford,1961
3. Continuous maps on block designs;Dinitz;Ars Combin.,1982
4. Continuous maps in finite projective spaces;Dinitz;Congr. Numer.,1982
5. Translational hulls and block designs;Dinitz;Semigroup Forum,1983