1. Space Policy Directive-1: Reinvigorating America's Human Space Exploration Program;Fed. Regist,2018
2. Liberate the Red Planet;Haqq-Misra,2016
3. Should and could humans go to Mars? Yes, but not now and not in the near future;Szocik;Futures,2019
4. International Space Agencies Meet to Boost Coordination toward Moon-To-Mars Exploration,2019