Ore Oystein <br/><br/>
Four-colour problem 

 - New York       Academic Press         1977 
 - xv, 259p.  cm. 
 - Pure and applied mathematics; 27 .
<br/><br/> Bibliography 249-254p 
<br/><br/><label>Standard No.: </label>24388 
<br/><br/><label>Source: </label> Textual 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Grapth theory
<br/><br/><label>Dewey Class. No.: </label>B44, K7