GRAV3D manual: 
References

Haaz, I. B., 1953, Relationship between the potential of the attraction of the mass contained in a finite rectangular prism and its first and second derivatives, Geofizikai Kozlemenyek, II, No 7.

Li, Y. and Oldenburg, D. W., 1997, Fast inversion of large scale magnetic data using wavelets, 67th Ann. Internat. Mtg., Soc. Expl. Geophys., Expanded Abstracts, 490–493.

Li, Y. and Oldenburg, D. W., 1998, 3D inversion of gravity data, Geophysics, 63, 109–119

Nagy, D. 1966, The gravitational attraction of a right rectangular prism, Geophysics, 31, 361–371.