1. Allport, F. H. 1924.Social psychology, xiv+453Boston: Houghton Mifflin.
2. Bertalanaffy, L. V. 1933.Theoretische Biologie, ix+349Berlin: Borntraeger.
3. A methodological consideration of the problem of psychometrics
4. Freud and the Scientific Method
5. Campbell, N. T. 1920.Physics—the elements, 565.Cambridge: University Press.