Cita APA (7a ed.)

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

Cita Chicago Style (17a ed.)

Freitag, Herta Taussig, y Arthur H. Freitag. The Number Story. Washington: National Council of Teachers of Mathematics, 1960.

Cita MLA (8a ed.)

Freitag, Herta Taussig, y Arthur H. Freitag. The Number Story. National Council of Teachers of Mathematics, 1960.