Sherwood, Martin. <br/><br/>
Isaac Asimov. 

 - Washington-XXU :   U.S. Information Agency,   1975. 
 - p. 62-64 :   il. 
 - Bimestral 
 - No. 8(1975) 
 - Horizonte Usa ;   No. 8 .
 - U.S. Information Agency. .
<br/><br/><br/>Espaņol.