3Dijkstra E W. A note on two problems in connection with graphs[J].Numer. Math., 1959, 1:269-271.
4Nakanishi I, Yamaguchi K. A numerical experiment on nonlinear image reconstruction from first-arrival times for two-dimensional island arc structure[J]. J. Phys. Earth, 1986, 34:195-201.
5Moser T J. Shortest path calculation of seismic rays[J]. Geophysics,1991, 56(1): 59-67.
6Klimes L, Kvasnicha M. 3-D network ray tnlcing[J], Geophys. J.Int., 1994, 116:726-738.
7Zhang J,Toksoz M N. Nonlinear refraction traveltime tomography[J].Geophysics, 1998, 63:1726- 1737.
8Moser T J, Van Eck T, Nolet G. hypocenter determination in strongly heterogeneous earth models using the shortest path method[J]. J. Geophys. Res., 1992, 97:6563 -6572.
9Fischer R,Lees J M. Shortest path my tracing with sparse graphs[J].Geophysics, 1993, 58:987-996.
10Van Avendonk H J A, Harding A J, Orcutt J A, Holbrook W S. Hybrid shortest path and ray bending method for traveltime and raypathc calcuations[J]. Geophysics, 1982,66(2) :648 - 653.