Ellsworth, William L. (1991). "The Richter Scale ML". In Wallace, Robert E. (ed.). The San Andreas Fault System, California. USGS. p. 177. Professional Paper 1515. Archived from the original on April 25, 2016. Retrieved 2008-09-14.
Ellsworth, William L. (1991). "The Richter Scale ML". In Wallace, Robert E. (ed.). The San Andreas Fault System, California. USGS. p. 177. Professional Paper 1515. Archived from the original on April 25, 2016. Retrieved 2008-09-14.