1. 1980s: All Eyes Focus on Space Shuttle, 6 June, viewed 9 September 2018, https://www.nasa.gov/centers/kennedy/about/history/timeline/80s-decade.html.
2. Public opinion and the development of space technology;Almond;The Public Opinion Quarterly,1960
3. The Sixties;Anderson,2011
4. Astronauts land on plain; collect rocks, plant flag,1968