­Despertad! ;   vol. LI, no.4 

 - Estados Unidos-US :   Watch Tower Society,   1970. 
 - p. 29-31 :   il. 
 - Quincenal 
 - Vol. LI, no. 4(Feb. 1970) 
 - ­Despertad! ;   vol. LI, no.4 .
 - Watch tower Society. .