mfb,the references used in the above posted link are :
Aldrin, Buzz with David Noland. 2005. "Buzz Aldrin's roadmap to Mars—a PM exclusive." Popular Mechanics, December 14, 2005.
http://www.popularmechanics.com/science/space/moon-mars/2076326
Chang, Kenneth. 2010. "NASA gets new orders that...