APA

Freitag H. T., Freitag A. H., . (1960). The number story. Washington: National Council of Teachers of Mathematics.

Chicago

Freitag Herta Taussig, Freitag Arthur H, . 1960. The number story. Washington: National Council of Teachers of Mathematics.

Harvard

Freitag H. T., Freitag A. H., . (1960). The number story. Washington: National Council of Teachers of Mathematics.

MLA

Freitag Herta Taussig, Freitag Arthur H, . The number story. Washington: National Council of Teachers of Mathematics. 1960.