MARKS, J. L., PURDY, C. R., & KINNEY, L. B. (1958). Teaching aritmetic for understanding. McGraw-Hill Bo. Co.

MARKS, John L., C. Richard PURDY, and Lucien B. KINNEY. Teaching Aritmetic for Understanding. New York: McGraw-Hill Bo. Co, 1958.

MARKS, John L., et al. Teaching Aritmetic for Understanding. McGraw-Hill Bo. Co, 1958.