Ashlock  <br/><br/>
Error patterns in computation : a semi-programmed approach  
/ Robert B. Ashlock. 
 - 9th ed.. 
 - Columbus  Charles Merrill Pub. Co.  2006. 
 - x, 274p.  ill.  24cm 
<br/><br/> Includes index 
<br/><br/><label>ISBN: </label>0131198866  
<br/><br/><label>Subjects--Topical Terms: </label><br/>Arithmetic--Study and teaching (Elementary)
<br/><br/><label>Dewey Class. No.: </label>372.72044 ASH 2006