1. K. ARNOLD: “An Attempt to Determine the Unknown Parts of the Earth’s Gravity Field by Successive Satellite Passages”,Bull. Géodésique 87, 97, 1968.
2. E. BUCHER: “Motion of the Nodal Line of the Second Russian Earth Satellite and Flattening of the Earth”,Nature, Vol.182, pp. 198–199, 1958.
3. Irene FISCHER, F.R. SHIRLEY, and Sandra TODD: “Specific practical applications of satellite geodesy”,Surveying and Mapping,30, 541–551, 1970.
4. E.M. GAPOSCHKIN, and K. LAMBECK:1969 Smithsonian Standard Earth (II), SAO Special Report 315, 1970.
5. L. GULICK: “A Comparison of Methods for Computing Gravitational Derivatives”, ESSA Technical Report C&GS 40, 1970.