1. C.F. BAESCHLIN: Lehrbuch der Geodäsie, Orell Füssli Verlag, Zürich 1948.
2. A. BJERHAMMAR: A solution of the gravimetric boundary value problem for a “continuous” gravity field, Royal Inst. of Technology, Stockholm 1965
3. A. BJERHAMMAR: On the theory of a new geoid, USAEGIMRADA Res. Inst. for Geodetic Sci., Alexandria (Virg.) 1967.
4. R. COURANT and D. HILBERT: Methods of mathematical physics, vol. 1. Interscience Publ., New York 1953.
5. G. FALK: Theoretische Physik, Heidelberger Taschenbücher, Bd. 1 u. la, Springer-Verlag, Berlin, Heidelberg, New York 1966