Colangelo, G., J. Heinicke, U. Koch, V. Lapenna, G. Martinelli, and L. Telesca. “Results of Gas Flux records in the Seismically Active area of Val d’Agri (Southern Italy)”. Annals of Geophysics, vol. 48, no. 1, Dec. 2005, doi:10.4401/ag-3179.