"Winter, James De" <br/><br/>
How to catapult a castle: machines that brought down the battlements 

 - Minnesota  Capstone Press  2008 
 - 32 
 - Fact finders Extreme .
<br/><br/> "Presents the science behind building and defending castles including the use of simple machines, such as pulleys and levers"--Provided by publisher 
<br/><br/><label>ISBN: </label>9781429631181 
<br/><br/><label>Dewey Class. No.: </label>000  / EXT