1. Peters T. NASA Johnson Space Center. Electronic communication, 8 September 1998
2. Rapp D. A review of Mars ISPP technology. Jet Propulsion Laboratory, Pasadena, CA, 28 July 1998
3. Mueller P. Hydrogen transport to Mars for in-situ propellant production-based sample return. Space Dynamics Laboratory Report SDL/98-032, Contract 961007, Space Dynamics Laboratory, Utah State University, Logan, UT, 17 April 1998
4. Drake B, editor. Reference mission version 3.0, addendum to the human exploration of Mars: the reference mission of the NASA Mars Exploration Study Team, section 5.3.5, all solar scenario. NASA Exploration Office, 1998 June (http://www_sn.jsc.nasa.gov/EXPLORE/addendum/A5.htm#A5.0)
5. Paulsen B, Agren J, Batty J. Autonomous thermal disconnect devices. Presented at 1999 Cryogenic Engineering Conference and International Cryogenic Materials Conference, Montreal, Quebec, Canada, 12–16 July 1999 (To be published in Advances in Cryogenic Engineering. New York: Plenum Press)