Arithmetic Teacher 39 

 - Philadelphia  NCTM  Nov. 1991 
 - 60 
 - 20091211 
 - Arithmetic Teacher  39 .
<br/><br/><label>ISSN: </label>1679-656X 
<br/><br/><label>Dewey Class. No.: </label>AMT 2009  / 2009