APA (7th ed.) Citation

Ellis, R. S. (1930). The psychology of individual differences. D. Appleton and Co.

Chicago Style (17th ed.) Citation

Ellis, Robert Sidney. The Psychology of Individual Differences. New York: D. Appleton and Co, 1930.

MLA (9th ed.) Citation

Ellis, Robert Sidney. The Psychology of Individual Differences. D. Appleton and Co, 1930.