Ashlock, Robert B. <br/><br/>
Error patterns in computation  a semi-programmed approach 
Robert B. Ashlock. 
 - 3rd. ed. 
 - Columbus [Ohio]  Merrill Pub. Co.  c1982. 
 - ix, 197 p.  ill. 
<br/><br/>Bibliography: p. 161-178. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Arithmetic--Study and teaching (Elementary)
<br/><br/><label>LC Class. No.: </label>QA135.5  / .A782 1986 
<br/><br/><label>Dewey Class. No.: </label>372.7/2044