1. Publ. Spec.;C. Morelli,1974
2. J. J. Levallois:Bull. Géod.,99, 111 (1971).
3. C. Morelli:Boll. Geod. Sc. Aff., Firenze.,19, 4 (1960).
4. G. Cerutti, L. Cannizzo, A. Sakuma andJ. Hostache:A transportable apparatus for absolute gravity measurements, V.D.I. Berichte 212, 49/51 (1974).
5. A. H. Cook:Bull. Geod., No. 44 34 (1957).