Cita APA (7th ed.)
Spitzer, H. F. Enrichment of Arithmetic (1a.ed.). Webster Divsion McGraw - Hill.
Cita Chicago (17th ed.)
Spitzer, Herbert F. Enrichment of Arithmetic. 1a.ed. Buenos Aires: Webster Divsion McGraw - Hill.
Cita MLA (9th ed.)
Spitzer, Herbert F. Enrichment of Arithmetic. 1a.ed. Webster Divsion McGraw - Hill.
Atenció: Aquestes cites poden no estar 100% correctes.