JOHNSTON, C. L., WILLIS, A. T., & HUGHES, G. M. (1984). Essential arithmetic.-- ed. 4. Wadsworth Pub. Co.
Lua i Stíl Chicago (17ú heag.)JOHNSTON, C. L., Alden T. WILLIS, agus Gale M. HUGHES. Essential Arithmetic.-- Ed. 4. Belmont: Wadsworth Pub. Co, 1984.
Lua MLA (9ú heag.)JOHNSTON, C. L., et al. Essential Arithmetic.-- Ed. 4. Wadsworth Pub. Co, 1984.
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