CAPUTO, M., L. KNOPOFF, E. MANTOVANI, S. MUELLER, and G. F. PANZA. “Rayleigh Wave Phase Velocities and Upper Mantle Structure in the Apennines”. Annals of Geophysics, vol. 29, no. 4, Nov. 1976, pp. 199-14, doi:10.4401/ag-4804.