- http://www.nasa.gov/centers/johnson/about/resources/jscfacts/index.html
- http://www.history.com/topics/space-race
- http://www.windows2universe.org/space_missions/unmanned_table.html
- http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=MERCR3
- http://www.nasa.gov/mission_pages/mercury/missions/freedom7.html
- http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=MERCR3