Ore, Oystein, 1899-1968.  Ore, Oystein, 1899-1968. <br/><br/>
The four-color problem. 

 - New York,  Academic Press,  1967. 
 - Pure and applied mathematics; a series of monographs and textbooks ;  27 .
 - Pure and applied mathematics (Academic Press) ;  27. .
<br/><br/>Bibliography: p. 249-253. 
<br/><br/><label>LCCN: </label>66030095 //r86 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Four-color problem.
<br/><br/><label>LC Class. No.: </label>QA3  / .P8 no. 27 
<br/><br/><label>Dewey Class. No.: </label>513/.83