Austere Human Missions to MarsArchived 2016-01-31 at the Wayback Machine, Hoppy Price, Jet Propulsion Laboratory, Alisa M. Hawkins, Torrey O. Radcliffe, The Aerospace Corporation, September 2009, retrieved December 25, 2015
Austere Human Missions to MarsArchived 2016-01-31 at the Wayback Machine, Hoppy Price, Jet Propulsion Laboratory, Alisa M. Hawkins, Torrey O. Radcliffe, The Aerospace Corporation, September 2009, retrieved December 25, 2015