WALKER, H. M. (1951). Mathematics essential for elementary: Statistics; a self-teaching manual. Holt, Rinehart and Winston.
Cita Chicago (17th ed.)WALKER, Helen M. Mathematics Essential for Elementary: Statistics; a Self-teaching Manual. New York: Holt, Rinehart and Winston, 1951.
Cita MLA (9th ed.)WALKER, Helen M. Mathematics Essential for Elementary: Statistics; a Self-teaching Manual. Holt, Rinehart and Winston, 1951.
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