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6Zur Rolle der Sprache in Erkenntnistheoretischer HinsichtJournal of Symbolic Logic 43 (1): 151. 1978.
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19Müller G. H.. Über die unendliche Induktion. Infinitistic methods, Proceedings of the Symposium on Foundations of Mathematics, Warsaw, 2-9 September 1959, Panstwowe Wydawnictwo Naukowe, Warsaw, and Pergamon Press, Oxford, London, New York, and Paris, 1961, pp. 75–95 (review)Journal of Symbolic Logic 40 (4): 627-627. 1975.
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15Lorenzen Paul. Über das Prinzip “ex falso quodlibet.” Methodos, Bd. 3 , S. 43–46Journal of Symbolic Logic 19 (4): 298-298. 1954.
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10Becker Oskar. Einführung in die Logistik, vorzüglich in den Modalkalkül. Westkulturverlag Anton Hain, Meisenheim am Glan 1951, 92 S (review)Journal of Symbolic Logic 17 (1): 59-60. 1952.
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2Einführung in die Logistik, Vorzüglich in den ModalkalkülJournal of Symbolic Logic 17 (1): 59-60. 1952.
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28Equational Logic and Equational Theories of AlgebrasJournal of Symbolic Logic 36 (1): 161-162. 1971.
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23Ein Wohlordnungsbeweis für das OrdinalzahlensystemT(J)Archive for Mathematical Logic 27 (1): 5-20. 1988.A recursive notation system of a strong segment of ordinals was developped by Jäger [3]. An unessential modified versionT(J) of this notation system was described in [4]. In the following, the well-ordering ofT(J) is proved in a formal system of second order arithmetic with the axiom schema ofΠ 2 1 -comprehension. It follows, that the proof theoretical ordinal ofΠ 2 1 -analysis is greater than the order type ofT(J)