Necessary truth: a book of readings /
edited by L.W. Sumner, John Woods 
. - New York : Random House,  1969 
. - vi, 226 p.  20 cm. 
 - (Studies in philosophy )(A Random House study in the history of philosophy )
 -  SPH 23 .
<br/>К.: Бібліогр. : c. 207-223, Index