APA (7th ed.) Citation

Schaaf, W. L. (1970). A bibliography of recreational mathematics ([4th ed.].). National Council of Teachers of Mathematics.

Chicago Style (17th ed.) Citation

Schaaf, William Leonard. A Bibliography of Recreational Mathematics. [4th ed.]. Washington: National Council of Teachers of Mathematics, 1970.

MLA (9th ed.) Citation

Schaaf, William Leonard. A Bibliography of Recreational Mathematics. [4th ed.]. National Council of Teachers of Mathematics, 1970.