1. School of Geology and Geophysics, University of Oklahoma, Norman, OK 73019
2. Seismograph Service Corporation, P.O. Box 1590, Tulsa, OK 74102
3. Marathon Oil Company, P.O. Box 552, Midland, TX 79702
4. Shell Oil Company, P.O. Box 831, Houston, TX 77001
5. Conoco Inc., 1 Lakeview Energy Center, 3817 NW Expressway, Oklahoma City, OK 73112