1. The nature of human intelligence;Guilford,1967
2. Cognitive systems principles of leveling and sharpening;Holzman;Journal of Psychology,1954
3. Information processing and the child;Kagan;Psychological Monographs,1964
4. The handbook of psychological testing;Kline,2000
5. Minding our p's and q's: on finding relationships between learning and intelligence;Lohman,1999