Freitag, H. T., & Freitag, A. H. (1960). The number story. National Council of Teachers of Mathematics.
Chicago Style (17th ed.) CitationFreitag, Herta Taussig, and Arthur H. Freitag. The Number Story. Washington: National Council of Teachers of Mathematics, 1960.
MLA (8th ed.) CitationFreitag, Herta Taussig, and Arthur H. Freitag. The Number Story. National Council of Teachers of Mathematics, 1960.
Advarsel: Disse citationer er muligvist ikke 100% nøjagtige.