1. Newell, Homer: Beyond the atmosphere - early days of space science. Washington DC, NASA, SP-421.
2. For an analysis of the key decisions of this period, see Logsdon, John: After Apollo - Richard Nixon and the American space program. New York, Palgrave Macmillan, 2015
3. Ezell, Linda Neuman: NASA historical data book, Programs and projects, vol. II 1958-68; vol. III, 1969-78. Washington DC, NASA, SP-4012.
4. MacNeil, Nick, Carter-Mondale Transition Planning Group: NASA recommendations, 31st January 1977.
5. Logsdon, John: The survival crisis of the U.S. solar system exploration program. 2012, Palmgrave McMillan. Originally an unpublished paper for the NASA History Office, 1989.