Ellsworth, William L. (1991). "The Richter Scale ML". In Wallace, Robert E. (ed.). The San Andreas Fault System, California. United States Geological Survey. p. 177. Professional Paper 1515. Archived from the original on April 25, 2016. Retrieved September 14, 2008.
Woo, Wang-chun (September 2012). "On Earthquake Magnitudes". Hong Kong Observatory. Archived from the original on May 24, 2017. Retrieved December 18, 2013.
Ellsworth, William L. (1991). "The Richter Scale ML". In Wallace, Robert E. (ed.). The San Andreas Fault System, California. United States Geological Survey. p. 177. Professional Paper 1515. Archived from the original on April 25, 2016. Retrieved September 14, 2008.
Woo, Wang-chun (September 2012). "On Earthquake Magnitudes". Hong Kong Observatory. Archived from the original on May 24, 2017. Retrieved December 18, 2013.