National council of teachers of mathematics <br/><br/>
El sistema de los enteros/ 
National council of teachers of mathematics 
 - 80p/23cm 
 - Col. temas de matemáticas No. 9 .
<br/><br/><label>Subjects--Topical Terms: </label><br/>NUMEROS, TEORIA DE LOS
<br/><br/><label>Dewey Class. No.: </label>512.7  / NAT 1975