GoldsteinK.ScheererM.Abstract and concrete behaviour; an experimental study with special tests. Psychological Monographs, 1941, 53, No. 2 (Whole No. 239).
2.
OlverR. R.HornsbyJ. R.On equivalence. In BrunerJ. S. (Eds.), Studies in cognitive growth. New York: Wiley, 1966. Pp. 68–85.
3.
WarrP. (Ed.) Thought and personality. London: Penguin, 1970.