00526nam a2200145Ia 4500001000700000003000500007005001700012008004100029110006000070245008400130260004200214300001300256500007500269650003600344118252BIBL20160527184654.0780406m1970 mx 00010 spa 2 aNational Council of Teachers of Mathematics.wcn2Local13aEl sistema de los números racionales ; traducción de Federico Velasco Coba. aMéxicobEditorial F. Trillasc1970. av.bill. aTranslation of : Topics in Mathematics for Elementary School Teachers. 0aArithmeticxFoundations.2Local