References
- Blommers , P. and Lindquist , E. F. 1960 . Elementary statistical methods in psychology and education , Boston : Houghton Mifflin .
- Hays , W. L. 1973 . Statistics for the social sciences , New York : Holt .
- Novick , M. R. and Jackson , P. H. 1974 . Statistical methods for educational and psychological research , New York : McGraw-Hill .