Holt, M., & Dienes, Z. P. (1973). Let's play math. Penguin Books.
Cita Chicago (17th ed.)Holt, Michael, i Zoltan Paul Dienes. Let's Play Math. Middlesex, Eng: Penguin Books, 1973.
Cita MLA (9th ed.)Holt, Michael, i Zoltan Paul Dienes. Let's Play Math. Penguin Books, 1973.
Atenció: Aquestes cites poden no estar 100% correctes.