Naoi, M.; Nakatani, M.; Yabe, Y.; Kwiatek, G.; Igarashi, T.; Plenkers, K. (2011): Twenty Thousand Aftershocks of a Very Small (M 2) Earthquake and Their Relation to the Mainshock Rupture and Geological Structures. Bulletin of the Seismological Society of America, 101, 5, 2399-2407.