REFERENCES
- D'ltri , P. A. and D'ltri , F. M. 1977 . Mercury Contamination: A Human Tragedy , New York : John Wiley and Sons .
- Joyce , B. , Weil , M. and Showers , B. 1992 . Models of Teaching , London : Allyn and Bacon .
- Piaget , J. 1952 . The Origins of Intelligence in Children , New York : W.W.Norton .
- Saint-Laurent C. ( 1992 ). UNCED – The Way Forward . WWF International publication .
- Sprinthall , N. A. and Sprinthall , R. C. 1990 . Educational Psychology – A Developmental Approach , London : McGraw-Hill International Editions .
- White , R. 1959 . Motivation reconsidered: The concept of competence . Psychological Review , 66 : 279 – 333 .