http://www.nasa.gov/worldbook/artificial_satellites_worldbook.html

http://www.gma.org/surfing/sats.html

http://en.wikipedia.org/wiki/Satellites

http://www.popsci.com/taxonomy/term/41113/

http://www.noaa.gov/satellites.html

http://en.wikipedia.org/wiki/Earth_observation_satellite

http://www.satobs.org/observe.html

http://www.space.com/spacewatch/satellite_hunting_020524.html

http://www.gearthblog.com/satellites.html

http://www.nasa.gov/audience/forstudents/5-8/features/what-is-a-satellite-58.html