1. E.G. Boring,A History of Experimental Psychology, Appleton-Century-Crofts, New York.
2. R. Carnap,Der logische Aufbau der Weit, Weltkreis-Verlag, Berlin.
3. R. Carnap, “Testability and Meaning,”Philosophy of Science, 3, 1936, 420–71 and 4, 1937, 2–40.
4. R. Carnap,The Logical Syntax of Language, Routledge and Kegan Paul, London.
5. V. Fano,Matematica ed Esperienza nella fisica moderna, Accademia Nazionale di Scienze Lettere e Arti di Modena, Il Ponte Vecchio, Cesena.