1. Earth's shape and potential;de Graaff-Hunter;Tydschrift voor Kadaster en Landmeetkunde,1961
2. The shape of the Earth expressed in terms of gravity at ground level;de Graaff-Hunter;Bull. Géodésique,1960
3. Imperfections in finding Earth shape from gravity and some suggestions for improvement;de Graaff-Hunter;Bull. Geodesique,1965
4. Determination of the even harmonics in the Earth's gravitational potential;King-Hele;Geophys. J.,1963