1. Public opinion polls and perceptions of US spaceflight;Launius;Space Policy,2003
2. See, for example:
3. M. Dittmar, Engaging the 18–25 generation: educational outreach, interactive technologies and space, American Institute of Aeronautics and Astronautics, Copyright 2006 Dittmar Associates Inc., 2006.
4. M. Dittmar, The Market study for space exploration, Dittmar Associates Inc., 2004, 〈http://www.dittmar-associates.com〉
5. L. Billings, 50 Years of NASA and the public: what NASA? What publics? NASA's first 50 years: an historical perspective, NASA History Office, Washington, DC, 2010, in press.