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2. P. Bernays, “Remarques sur le Probleme de la Decision en Logique Elementaire,” Edition de Centre Nat. de la Recb. Scient. (Paris), vol. 13, pp. 39–44 (1958).
3. J. R. Buchi, “Turing Machines and the Entscheidungsproblem.” Matbematiscbe Ann., vol. 148, pp. 201–213 (1962).
4. J. R. Buchi, Abstract of Ref. 3, Natices Amer. Matb. Soc., vol. 8, p. 354 (1961).
5. Ann. Harvard Computation Lab.;B Dreben,1962