1. Products of automata and the problem of covering;Ginzburg;Am. Math. Soc.,1965
2. Universal Algebra;Grazer,1966
3. Algebraic Structure Theory of Sequential Machines;Hartmanis,1966
4. Homomorphisms of Graphs and Automata;Hedetniemi,1966
5. The theory of models with generalized atomic formulas;Keisler;J. Symbolic Logic,1960