9Bozzolo D, Pamini R. Simulation of Rockfalls down a Valley Side [J]. Acta Mechanica, 1986, 63: 113-130.
10Azzoni A, Lag G, Zaninetti A. Analysis and Prediction of Rockfalls Using a Mathematical Model [J]. International Journal of Rock Mechanics and Mining Science, 1995, 32 (7): 709-724.