1. G.A. Landis, Footsteps to Mars: an incremental approach to Mars exploration, in: Presented at Case for Mars V, Boulder, CO, 26–29 May 1993; paper in Journal of the British Interplanetary Society, 48 (1995) 367–342. Reprinted in From Imagination to Reality: Mars Exploration Studies, AAS Science and Technology Series, vol. 91, 1997, pp. 339–350.
2. Robots and humans: synergy in planetary exploration;Landis;Acta Astronautica,2004
3. Acute respiratory effects of particles: mass or number?;Osunsanya;Occupational and Environmental Medicine,2001
4. Lifetime risk of silicosis death for quartz exposed workers among German population;Sun;Occupational and Environmental Medicine,2004
5. A.J. Willoughby, Multinational exploration of Mars: an affordable concept, in: Paper IAF-88-390, 39th Congress of the IAF, October 1988.