1. Berman, D. and Forward, R. L.: 1968,Exploitation of Space for Experimental Research, Vol. 24. Advances in the Astronautical Sciences, American Astronautical Society.
2. Hildebrand, F. B.: 1964,Advanced Calculus for Applications, Prentice-Hall, Inc., Englewood Cliffs, N.J., p. 348.
3. Jacchia, L. G.: 1969,annals of the IQSY, Vol. 5, Solar-Terrestrial Physics: Terrestrial Aspects, MIT Press, Cambridge, Mass., pp. 323?39.
4. United States Standard Atmospheric Supplements 1966, Sponsored by ESSA, NASA, and the U.S. Air Force, pp. 220?89.
5. Wilk, L. S.: 1969, ?A Gravitational Experiment in Space?, unpublished communication.