Frost, Helen <br/><br/>
What Are Pulleys? 

 - USA  Capstone Press  1949 
 - 24 
<br/><br/><label>ISBN: </label>0-7368-0847-7 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Juvenile Non-Fiction<br/>Pulleys<br/>Science<br/>Simple Machine