Kells Lyman M. <br/><br/>
Plane and spherical trigonometry / 
Lyman M. Kells, Willis F. Kern, James R. Bland. 
 - Second edition. Thirteenth impression. 
 - New York ;  London :  McGraw-Hill book Company Inc,  1940. 
 - (wiele liczbowań) :  ilustracje ;  24 cm. 
<br/><br/>Indeks.