1. Theories of Abstract Automata;Arbib,1969
2. Syntax and semantics: a categorial view;Benson;Information and Control,1971
3. On the syntactic structures of unrestricted grammars. II. Automata;Buttelmann;Information and Control,1975
4. Grammars without syntactic variables;Buttelmann,1974
5. Three models for the description of language;Chomsky;IRE Trans. Inform. Theory,1956