1. IEEE Std. 80-2000, IEEE Guide for Safety in AC Substation Grounding, IEEE: Institute of Electrical and Electronic Engineers, Inc., New York, 2000.
2. IEEE Std. 81-1983, IEEE Guide for Measuring Earth Resistivity, Ground impedance, and earth surface potentials of a ground system, IEEE: Institute of Electrical and Electronic Engineers, Inc., New York, 1983.
3. J.G. Aderson, Lightning Performance of Transmission Line, Chapter 12, Transmission Line Reference Book, 345kV and above, 2nd.ed., EPRI-Electric Power Research Institute, Palo Alto, California, 1982.
4. J. Carmona, J. Fuentes, Optimization of the Building Costs of Grounding Grids in Substations, in: Proceedings of the V Congreso de Generación y Transmisión de Energía Eléctrica, Caracas, Venezuela, 1989 (in Spanish).
5. J.A. Blandón, State of the Art in the Design of Grounding Grids in Substations, Report no. 16 of Electroporcelana GAMMA S.A, 1998, available in http://www.gamma.com.co/htm/esp-bol02.html (in Spanish).