Trafton, P. R. (1989). New directions for elementary school mathematics. National Council of Teachers of Mathematics.
Chicago-referens (17:e uppl.)Trafton, Paul R. New Directions for Elementary School Mathematics. Reston, Va.: National Council of Teachers of Mathematics, 1989.
MLA-referens (8:e uppl.)Trafton, Paul R. New Directions for Elementary School Mathematics. National Council of Teachers of Mathematics, 1989.
Varning: dessa hänvisningar är inte alltid fullständigt riktiga.