1. Stability of interests within an occupation over 30 years;Campbell;J. appl. Psychol.,1966
2. The vocational interests of APA presidents;Campbell;Amer. Psychologist,1965
3. Ability, interests and aptitude;Ferguson;J. appl. Psychol.,1960
4. Life insurance interest, ability and termination of employment;Ferguson;Life insur. agency management assoc. personnel J.,1958