Azzaro, R., and M. S. Barbano. “Relationship Between Seismicity and Eruptive Activity at Mt. Etna Volcano (Italy) As Inferred from Historical Record Analysis: The 1883 and 1971 Case Histories”. Annals of Geophysics, vol. 39, no. 2, Nov. 1996, doi:10.4401/ag-3981.