1. The 2019 U.S. Government official debris mitigation standard practices;Liou;Orbital Debris Quarterly Ners,2020
2. Satellite database release 2-1-14;Including Launches through January,2014
3. Satellite Database Release 4-1-20, Including Launches through March 31,2020
4. Progressive Leadership in Space Safety Requires a New Approachto Seting Debris Mitigation Standards”, 71st International Astronautical Congress;Maclay,2020
5. ESA's Annual Space Environment Report”,2021