1. 1) Good, C. V. "Dictionary of Education" 3rd edition, p. 220, McGraw-Hill, 1973
2. 2) Bloom, B. S, "Handbook Formative and Summative Evaluation of Student Learning" McGraw Hill, 1973
3. 3) Welch W, W., "Twenty Years of Science Curriculum Development: A Look Back". Review of Research in Education, pp. 282-306, 1979
4. 4) "Science Curriculum Improvement Study Teacher's Handbook", Lawlence Hall of Science, University of California, Berkley, 1974
5. 5) "Science 5/13 With-Objectives in Mind" Macdonald Educational, 1972