Kruif, Paul de. <br/><br/>
Can Man's Prime be Prolonged?. 

 - Nueva York-US  :   The Reader's Digest Association,   1944. 
 - página 21-24 :   ilustraciones full color 
 - Mensual 
 - Vol. 45, no. 267(Jul. 1944) 
 - The Reader's Digest  ;   no.267 .
 - The Reader's Digest Association. .