Ore, Oystein,  1899-1968. <br/><br/>
The four-color problem.  [[Book] /] 
Oystein Ore. 
 - New York :  Academic Press,  1967. 
 - xv, 259 p :  illus ;  24 cm. 
 - Pure and applied mathematics, a series of monographs and textbooks ;  27 .
<br/><br/>Bibliography: p. 249-253. 
<br/><br/> All Ages. 
<br/><br/><label>Subjects--Topical Terms: </label><br/>Four-color problem.
<br/><br/><label>Dewey Class. No.: </label>513.83 
<br/><br/><label>National Library of Medicine Call No.: </label> / O F