1. US Department of Defense. National Security Space Strategy [unclassifed summary]. 2011.
2. The Space Foundation, “The Space Report”, 2014, http://www.spacefoundation.org/sites/default/files/downloads/The_Space_Report_2014_Overview_TOC_Exhibits.pdf
3. The Space Foundation, “The Space Report”, 2015, https://www.spacefoundation.org/sites/default/files/downloads/The_Space_Report_2015_Overview_TOC_Exhibits.pdf
4. Air Force Space Command, “Ground-Based Electro-Optical Deep Space Surveillance”, http://www.afspc.af.mil/library/factsheets/factsheet_print.asp?fslD=3653&page=1. (25 February 2016)
5. 42nd AIAA/ASME/SAE/ASEE Joint Propulsion Conference & Exhibit