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[2] H. Bottenbruch: Übersetzung von algorithmischen Formelsprachen in die Programmsprachen von Rechenmaschinen. Zeit. für math. Logik und Grundlagen der Mathematik 4 (1958), 180-221. MR 0103154 | Zbl 0089.33201

[3] D. G. Cantor: On the Ambiguity Problem of Backus Systems. J. Assoc. Comp. Mach. 9 (1962), 477-479. DOI 10.1145/321138.321145 | MR 0150037 | Zbl 0114.33003

[4] Noam Chomsky: On certain Formal Properties of Grammars. Information and Control 2 (1959), 137-167. DOI 10.1016/S0019-9958(59)90362-6 | MR 0105365

[5] Noam Chomsky: Three Models for the Description of Language. IRE Trans. 1, T-2, No. 3 (1956), 113-124. (Russian translation: Kibernetičeskij sbornik 2 (1961), 237-266, Izd. in. lit., Moskva.)

[6] N. Chomsky, M. P. Schützenberger: The Algebraic Theory of Context-free Languages. Computer Programming and Formal Systems (ed. by P. Braffort and D. Hirschberg), Amsterdam 1963. MR 0152391

[7] Martin Davis: Computability and Unsolvability. New York, McGraw-Hill 1958. MR 0124208

[8] Francois Genuys: Commentaires sur le langage Algol. Chiffres 5 (1962), 29-53.

[9] Sheita A. Greibach: The Undecidability of the Ambiguity Problem for Minimal Linear Grammars. Information and Control 6 (1963), 119-125. DOI 10.1016/S0019-9958(63)90149-9 | MR 0160675

[10] Peter Zilahy Ingerman: A Syntax-Oriented Compiler for Languages whose Syntax Is Expressible in Backus Normal Form, and Some Proposed Extensions Thereto. University of Pennsylvania, The Moore School of Electrical Engineering, Philadelphia, Pennsylvania, April 1963.