1. Colorado School of MinesCenter for Gravity Electrical and Magnetic Studies 1600 Illinois St. Golden CO 80401 USA
2. U.S. Geological SurveyCrustal Geophysics and Geochemistry Science CenterDenver Federal Center Denver, CO 80225 USA
3. U.S. Army Corps. of EngineersEngineer Research and Development Center 3909 Halls Ferry Road Vicksburg, MS 39180 USA
4. XRI Geophysics 6207 Highway 80 East Vicksburg, MS 39180 USA