Marks, J. L., Purdy, C. R., & Kinney, L. B. (1970). Teaching elementary school mathematics for understanding. McGraw-Hill.
Lua i Stíl Chicago (17ú heag.)Marks, John L., C. R. Purdy, agus L. B. Kinney. Teaching Elementary School Mathematics for Understanding. New York: McGraw-Hill, 1970.
Lua MLA (9ú heag.)Marks, John L., et al. Teaching Elementary School Mathematics for Understanding. McGraw-Hill, 1970.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.