Johnston, C. L. & Willis, Alden T. <br/><br/>
Essential algebra 

 - Wadsworth publishing company, Inc., Belmont  1975 
 - 530 
<br/><br/><label>ISBN: </label>0-534-00410-5 
<br/><br/><label>Dewey Class. No.: </label>512 Joh/Wil