M. Anzidei, P. Baldi, A. Galvani, A. Pesci, I. Hunstad, and E. Boschi, “Coseismic displacement of the 27th September 1997 Umbria - Marche (Italy) earthquakes detected by GPS: campaigns and data”, Ann. Geophys., vol. 42, no. 4, Nov. 1999.