Osborn, Roger ...[et al] <br/><br/>
Extending mathematics understanding / 
Roger Osborn ...[et al] 
 - Columbus :  C. E. Merrill Books,  c 1961. 
 - 278 p. :  ill. :  24 cm. 
<br/><br/>Bibliography : p. 264-271. 
<br/><br/>339  339 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Mathematics--Study and teaching (Elementary)
<br/><br/><label>Dewey Class. No.: </label>510 / O2e