1. Radio signal source from unknown natural object;Dyson;The New York Times,1965
2. Energy resources;Hubbert;Natl Acad. Sci. Natl Res. Coun.,1962
3. Energy of the world of 2000 A.D.;Starr,1967
4. 2nd Progress Report of the Subcommittee on Science, Research and Development to the Committee on Science and Astronautics,1966
5. Energy sources of the future for the United States;Gaucher;Solar Energy,1965