1. and , “Science,” Encyclopedia of Educational Research, Macmillan, New York, 1960, p. 1228;
2. Ed., Policies for Science Education, Teachers College, Columbia University, New York, 1960, p. 32.
3. “Research on Teaching Science,” Handbook of Research on Teaching, American Educational Research Association, Rand McNally, Chicago, 1963, p. 1031.
4. “Commentary on Francis G. Cornell's Remarks: The Sampling Problem in Educational Research,” Research Design and Analysis, Second Annual Phi Delta Kappa Symposium on Educational Research, Phi Delta Kappa, Bloomington Illinois, 1961, p. 82; ref. 2, p. 1031.