Mold, Josephine. <br/><br/>
Counting machines /  
Josephine Mold. 
 - Cambridge :    Cambridge University Press,    1974. 
 - 32 p. :    ill. ;    22 cm. 
<br/><br/><label>ISBN: </label>0521203791 
<br/><br/><label>Subjects--Topical Terms: </label><br/> Numeration -- Juvenile literature.<br/> Mathematics -- Juvenile literature.<br/> Number systems.
<br/><br/><label>Dewey Class. No.: </label>513.2