1. An investigation on the value of drill work in the fundamental
operations of arithmetic.
2. Burton, Cassie B. “Results of Definite Drill in the Four Fundamental Processes as Shown by the Woody-McCall Mixed Fundamentals.” Fifth Yearbook of the Department of Elementary School Principals, pp. 323–328.
3. Coquillette, L. W. “A Comparative Analysis of Certain Drill Exercises in Arithmetic.” Master’s Thesis, unpublished. University of Iowa, 1927.
4. Crooks, D. D. “An Evaluation of Certain Remedial Drills on Problem Solving in Arithmetic.” Master’s Thesis, unpublished. University of Iowa, July, 1928.