1. E. DOUKAKIS: The Effect of Gravity Gradients in Point Coordination, M. Sc. thesis, Oxford University, England, 1976.
2. E.W. GRAFAREND: Three Dimensional Geodesy III—Refraction, Bull. Geod. e Sc. Aff., No. 2, pp. 153–160, 1976.
3. Department Geod. Sci. Rep.;E.W. Grafarend,1977
4. A. MARUSSI: Intrinsic Geodesy, Boll. Geod. e Sc. Aff., No. 1, pp. 1–35, 1976.