Zaliapin, Ilya and Gabrielov, Andrei and Keilis-Borok, Vladimir and Wong, Henry  (2008) Clustering Analysis of Seismicity and Aftershock Identification.  Physical Review Letters, 101 (1).  DOI: https://doi.org/10.1103/PhysRevLett.101.018501 <https://doi.org/10.1103/PhysRevLett.101.018501>