Hana, A. M. "Work Values in Relation to Age, Intelligence, Socioeconomic Level, and Occupational Interest Level." Unpublished Ed.D. thesis, Teachers College, Columbia University , 1954.
2.
O'Hara, R. P. and Tiedeman David V. "The Vocational Self Concept in Adolescence." Journal of Counseling Psychology, VI (1959),292-301.
3.
Super, D. E. and Overstreet, Phoebe L.The Vocational Maturity of Ninth Grade Boys. New York: Teachers College Bureau of Publications , 1960.
