Developing mathematical understandings in the upper grades [by] Leo J. Brueckner, Foster E. Grossnickle [and] John Reckzeh. Brueckner, Leo J. (Leo John), 1890-1967. Grossnickle, Foster E. (Foster Earl), 1896- Reckzeh, John. Mathematics Study and teaching (Secondary). QA11 .B848 510.7 BRD Philadelphia : Winston , 1957. 1957. 1957 Text v , 567 p. : eng