1. Butler, D.K., Ed. 1977, Proc. of the symposium on detection of subsurface cavities: U.S Army Engineer Waterways Experiment Station, CE, Vicksburg, MS.
2. Butler, D.K., 1983, Cavity detection research, Report 1, Microgravimetric and magnetic surveys, Medford Cave Site, Florida: Tech. Rep.GL-83-1, U.S Army Engineer Waterways Experiment Station, CE, Vicksburg, MS.
3. Owen, T. E., 1983, Detection and mapping of tunnels and caves: Developments, in Geophysical Exploration Methods, A. A. Fitch (ed.), Vol.5, 161-258 Applied Science Publishers Ltd.
4. Rumelhart, D.E., Hinton, G.E., and Williams, R.J., 1986: Learning internal representations by error propagation, in Rumelhart, D. E., and McClelland, J. L., Eds., Parallel distributed processing: Explorations in the Microstructure of Cognition,v.1, p.318-362, Cambridge, MA: The MIT Press.
5. Spichake, V., and Popova, I., 2000, Artificial neural network in inversion of magnetotelluric data in terms of three-dimensional earth macroparameters: Geophys. J. Intl.142, 15-26.