Sagan, Carl (October 2000) [1973]. Jerome Agel (ed.). Cosmic Connection: An Extraterrestrial Perspective. Freeman J. Dyson, David Morrison. Cambridge Press. ISBN0-521-78303-8. Վերցված է 2008 թ․ հունվարի 1-ին. «I would suggest Type 1.0 as a civilization using 1016 watts for interstellar communication; Type 1.1, 1017 watts; Type 1.2, 1018 watts, and so on. Our present civilization would be classed as something like Type 0.7.»
