Heywood, Ian. <br/><br/>
An Introduction to geographical information systems / 
Ian Heywood, Sarah Cornelius, Steve Carver. 
 - 4th  ed. 
 - Harlow, England :  Pearson Education,  2011. 
 - xxxiv, 446  p. 
<br/><br/><label>ISBN: </label>0273722595 : 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Geographic information systems.