5Boekaerts M, Boscolo P. Interest in learning, learning to be interested Learning and Instruction, 2002, 12:375-352
6Floyd FJ, Widaman KF. Factor analysis in the development and refinement of clinical assessment instruments. Psychological Assessment, 1995, 7:286-299
7Whitlock RV, Lubin B. Development of a measure that integrates positive and negative affect and personality: The comprehensive personality and affect scales. Journal Clinical Psychology, 2002, 58(9) : 1135-1156
8Gronbach LJ. Essentials of psychological testing. NewYork: Harper and Row Publisherslnc, 1990. 461-486