Gomberg, Joan and Reasenberg, Paul and Cocco, Massimo and Belardinelli, M. E.  (2005) A frictional population model of seismicity rate change.  Journal of Geophysical Research, 110 (B5).  pp. 1-10. DOI: https://doi.org/10.1029/2004JB003404 <https://doi.org/10.1029/2004JB003404>