1. Stability of the Future LEO Environment, IADC-12-08, Rev. 1https://www.iadc-online.org/Documents/IADC-2012-08,%20Rev%201,%20Stability%20of%20Future%20LEO%20Environment.pdf
2. Space Launch Report: Orbital Launch Summary by Yearhttp://www.spacelaunchreport.com/logyear.html
3. Union of Concerned Scientists Satellite Databasehttp://www.ucsusa.org/nuclear-weapons/space-weapons/satellite-database#.WhyVnVNrw2x
4. NASA's new breakup model of evolve 4.0
5. Space Situational Awarenesshttp://www.esa.int/Our_Activities/Operations/Space_Situational_Awareness/Space_Surveillance_and_Tracking_-_SST_Segment