1. J. Berstel and D. Perrin, The Theory of Codes (Academic Press. New York) to appear.
2. Propriétés combinatoires des codes biprefixes;Césari,1979
3. A. Ehrenfeucht and G. Rozenberg, Any regular code is included in a maximal regular code, to appear.
4. Automata, Languages and Machines, Vol. A;Eilenberg,1974
5. Codes asynchrones;Perrin;Bull. Soc. Math. de France,1977