The Director of the Central Earth Physics Institute Potsdam (Ed.)(1981): 4th International Symposium Geodesy and Physics of the Earth G.D.R. Karl-Marx-Stadt, May 12th-17th, 1980 PROCEEDINGS Part 3, (Veröffentlichungen des Zentralinstituts Physik der Erde ; 63.03), Potsdam : Zentralinstitut Physik der Erde, 528-836 p.https://doi.org/10.2312/zipe.1981.063.03