Guttman, L. "A Basis for Scaling Qualitative Data." American Sociological Review, IX (1944), 139-150.
2.
Likert, R. "A Technique for the Measurement of Attitudes." Archives of Psychology , XXII (1932), 1-55.
3.
Likert, R., Roslow, S. and Murphy, G. " A Simple and Reliable Method of Scoring the Thurstone Attitude Scales ." Journal of Social Psychology, V ( 1934), 228-238.
Pearson, Karl.Tables for Statisticians and Biometricians. Cambridge, Massachusetts: Cambridge University Press, 1914.
6.
Peters, C. C. and VanVoorhis, W. R.Statistical Procedures and Their Mathetmatical Bases . New York: McGraw-Hill Book Co ., 1940.
7.
Remmers, H. H. and Silance, E. B. "Generalized Attitude Scales ." Journal of Social Psychology, V ( 1934), 298-311.
8.
Silance, E. B. and Remmers, H. H. "An Experimental Generalized Master Scale: A Scale to Measure Attitude toward Any School Subject." Purdue University Studies in Higher Education, XXXV (1934), 84-87.
9.
Thurstone, L. L. and Chave, E. J.The Measurement of Attitude. Chicago: University of Chicago Press, 1929.
10.
Webb, Sam C.The Measurement and Prediction of College Students' Interest In Natural Science Subjects. Unpublished Doctoral Dissertation, University of North Carolina Library, Chapel Hill, N. C., 1948 .