Trafton, P. R. (1989). New directions for elementary school mathematics. National Council of Teachers of Mathematics.
Lua i Stíl Chicago (17ú heag.)Trafton, Paul R. New Directions for Elementary School Mathematics. Reston, Va.: National Council of Teachers of Mathematics, 1989.
Lua MLA (8ú heag.)Trafton, Paul R. New Directions for Elementary School Mathematics. National Council of Teachers of Mathematics, 1989.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.