1. http://www.execpc.com/~culp/space/timeline.html
2.. http://www.hq.nasa.gov/office/pao/History/sputnik/galleryex.html
3.
http://ham.spa.umn.edu/kris/animals.html
4. http://www.vibrationdata.com/space/Yuri.htm
5. http://grin.hq.nasa.gov/ABSTRACTS/GPN-2000-001023.html
6. http://www.capstonestudio.com/mercury/
7. http://starchild.gsfc.nasa.gov/docs/StarChild/whos_who_level2/tereshkova.html
8.
http://starchild.gsfc.nasa.gov/docs/StarChild/space_level2/leonov_spacewalk.html
9. http://images.jsc.nasa.gov/images/pao/GT4/10074017.jpg
10.
http://www.interspacenews.net/soyuz_spacecraft.ht
11. http://www.historyplace.com/unitedstates/apollo11/
12. http://www.nasm.edu/ceps/rpif/SSPR.html
13. http://www.lucidcafe.com/lucidcafe/library/96may/ride.html
14. http://www.nauts.com/bios/nasa/bluford.html
15. http://www.arlingtoncemetery.com/challengr.htm
16. http://www.fas.org/spp/51L.html
17. http://www.jpl.nasa.gov/galileo/lucid/index.html
18. http://mars.jpl.nasa.gov/MPF/index1.html
19. http://howstuffworks.lycos.com/space-station.htm