The Case for Mars V (Paperback) - Proceedings of the Fifth Case for Mars Conference Held May 26-29, 1993, at the University of Colorado, Boulder, Colorado
The Case for Mars VI (Hardcover) - Making Mars and Affordable Destination : Proceedings of the Sixth Case for Mars Conference Held July 17-20. 1996, at the University of Colorado
The Case for Mars V (Hardcover) - Proceedings of the Fifth Case for Mars Conference Held May 26-29, 1993, at the University of Colorado, Boulder, Colorado