Davidsen, Jörn and Grassberger, Peter and Paczuski, Maya  (2008) Networks of recurrent events, a theory of records, and an application to finding causal signatures in seismicity.  Physical Review E, 77 (6).  DOI: https://doi.org/10.1103/PhysRevE.77.066104 <https://doi.org/10.1103/PhysRevE.77.066104>