MATHEMATICS, N. C. O. T. O. (1963). Enrichment Mathematics for the Grades. National Council of Teachers of Mathematics.
Lua i Stíl Chicago (17ú heag.)MATHEMATICS, NATIONAL COUNCIL OF TEACHERS OF. Enrichment Mathematics for the Grades. National Council of Teachers of Mathematics, 1963.
Lua MLA (8ú heag.)MATHEMATICS, NATIONAL COUNCIL OF TEACHERS OF. Enrichment Mathematics for the Grades. National Council of Teachers of Mathematics, 1963.
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