1. Convergent and discriminant validation by the multitrait-multimethod matrix.
2. Christie, R. & Geis, F. L. (1970). Studies in Machiavellianism. New York: Academic.
3. Cohen, J. & Cohen, P. (1983). Applied multiple regression/correlation analysis for the behavioral sciences (2nd ed.). Hillsdale, NJ: Lawrence Erlbaum Associates, Inc.
4. Costa, P. T., Jr. & McCrae, R. R. (1992). NEO-PI-R professional manual. Odessa, FL: Psychological Assessment Resources.