Arnold, Virginia A. <br/><br/>
Observing 

 - 
 - U.S.A.  Macmillan/McGraw-Hill Publishing Company  1991 
 - 400 
<br/><br/><label>ISBN: </label>0021787204 
<br/><br/><label>Dewey Class. No.: </label>C. 372.4 Ar 7520 C1991