1. Motivation: Theory and research;Cofer,1964
2. Reinforcement effects of adult reactions and nonreactions on children's achievement expectations;Crandall;Child Development,1963
3. Verbal conditioning and clinical psychology;Greenspoon,1962
4. The value of praise and reproof as incentives for children;Hurlock;Archives of Psychology,1924
5. The effects of incentives upon the constancy of the I.Q.;Hurlock;Journal of Genetic Psychology,1925