Kuder, G. Frederic.Research Handbook, Kuder Preference Record Occupational, Form D. Chicago: Science Research Associates, 1956.
2.
Tilton, J. W. "The Measurement of Overlapping." Journal of Educational Psychology, XXVII (1937), 656-662.
3.
Zubin, J. "Nomographs for Determining the Significance of the Differences between the Frequencies of Events in Two Contrasting Series or Groups." Journal of the American Statistical Association, XXXIV (1939), 539-548.