1. V. Amar , G. Putzolu, On a family of linear grammars, Inf. & Control 7 (1964) 283–291
2. J. Berstel Transductions and Context-Free Languages, Teubner-Verlag, Stuttgart, 1979
3. M. Bird, The equivalence problem for deterministic two-tape automata, J.Comp.Syst.Sci.7 (1973) 218–236
4. L. Boasson , M. Nivat, Sur diverses familles de langages fermées par transduction rationnelle, Acta Informatics 2 (1973) 180–188
5. K.H. BÖhling, K. Indermark Endliche Automaten I, Bibliograph.Institut, Mannheim, 1969