ISBN 978-1-56347-260-2. National Aeronautics and Space Administration; Douglas A. Vakoch. Psychology of Space Exploration: Contemporary Research in Historical
Extraterrestrial Civilizations. New York: Scribner. 1981. ISBN 0684178427. Vakoch, Douglas A.; Dowd, Matthew F. (编). The Drake Equation: Estimating the Prevalence
Radio. 18 February 2022 [18 October 2022]. (原始内容存档于2022-12-29) (英语). Vakoch, Douglas A. Hawking's fear of an alien invasion may explain the Fermi Paradox