Darby, Gene. <br/><br/>
What is a simple machine / 
Gene Darby ; illustrated by Robert W. Friedl. 
 - Chicago  :  Benefic Press,  c 1961. 
 - 48 p. :  ill. ;  20 cm. 
 - The what is it series. .
<br/><br/>318  318 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Tools and fabricating equipment.
<br/><br/><label>Dewey Class. No.: </label>621.9 / D242w