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2. Carnap, R., 1932a, “Die physikalische Sprache als Universalsprache der Wissenschaft”, Erkenntnis 2, 432–465, trans. The Unity of Science, Kegan, Paul, Trench and Teubner & Co., London, 1934.
3. Carnap, R., 1932b, “Psychologie in physikalischer Sprache”, Erkenntnis 3, 107–142, trans. “Psychology in Physicalist Language”, in A.J. Ayer (ed.), Logical Positivism, Free Press, New York, 1959, 165–198.
4. Carnap, R. 1938, “Logical Foundations of the Unity of Science”, in International Encyclopedia of Unified Science, vol. 1 no.1, University of Chicago Press, Chicago, 42–62.
5. Carnap, R., 1963, “Intellectual Autobiography”, in P.A. Schilpp (ed.), The Philosophy of Rudolf Carnap, Open Court, La Salle, III. 3–84.