1. Aldrin, E. E., 1985. "Cyclic Trajectory Concepts," SAIC Presentation to the Interplanetary Rapid Transit Study Meeting, JPL.
2. Friedlander, A. L., J. C. Niehoff, D. V. Byrnes, and J. M. Longuski, 1986. "Circulating Transportation Orbits Between Earth and Mars," AIAA paper No. 86-2009-CP, AIAA/AAS Astrodynamics Conference, Williamsburg, VA, 1986.
3. Lo, M. and Ross, S. 2001. "The Lunar L1 Gateway: Portal to the Stars and Beyond," AIAA Space 2001 Conf., Albuquerque, NM, 28-30.