1. DRAKE, F. D., Discussion at Space Science Board-National Academy of Sciences Conference on Extraterrestrial Intelligent Life, November 1961, Green Bank, West Virginia.
2. The Search for Signals from Other Civilizations;VON HOERNER;Science,1961
3. CAMERON, A. G. W., Stellar Life Zones, Interstellar Communication, New York: W. A. Benjamin Co. (In press).
4. Interstellar Communication;MORRISON;Bulletin of the Philosophical Society of Washington,1962
5. The Rate of Star Formation. II: The Rate of Formation of Stars of Different Mass;SCHMIDT;The Astrophysical Journal,1963