The learning of mathematics : its theory and practice / edited by Howard F. Fehr. National Council of Teachers of Mathematics. Fehr, Howard F. (Howard Franklin), 1901- ed. Mathematics Study and teaching. QA1 .N3 21st 510.1 NAL Includes bibliographical references and index. Washington : National Council of Teachers of Mathematics, 1953. 1953. 1953 Text ix, 355 p. : eng Its Yearbook ; 21