Curtis, Francis D.Investigations of Vocabulary in Textbooks of Science for Secondary Schools. Boston : Ginn and Company, 1938. Pp. 21-36.
2.
Kyte, George C. "Experimentation in the Development of a Book to Meet Educational Needs." Education Administration and Supervision, XIV (1928), 86-100.
3.
Major, Alexander G. "Readability of College General Biology Textbooks and the Probable Effects of Readability Elements on Comprehension." Unpublished Ph.D. thesis, Syracuse University , 1955.
4.
Mallinson, G. G. "Textbook and Reading Difficulty in Science Teaching." Science Teacher, XXV (1958), 474-5.
5.
Marshall, James S. "The Relationship between Readability and Comprehension of High School Physics Textbooks." Unpublished Ph.D. thesis, Syracuse University, 1956.
6.
Warriner, David A. "An Investigation of the Effect of Certain Psychosemantic Factors of the Level of Reading Comprehension Difficulty in High School Chemistry and Physics." Unpublished Ph.D. thesis, Cornell University, 1951.
