1. How Nature Works: The Science of Self-Organized Criticality;Bak,1996
2. Observational evidence for earthquakes as a nonlinear dynamic process
3. Fractals and Chaos in Geology and Geophysics;Turcotte,1997
4. P. Bak, Nature Debates, http://www.nature.com/nature/debates/earthquake/equake_10.html.
5. Self-Organized Criticality;Jensen,1998