1. Center for Agricultural and Rural Development; Iowa State Univ.; Ames IA 50010-1070
2. USDA-ARS, Hydrology and Remote Sensing Laboratory; Bldg. 007, Rm. 104 BARC-West Beltsville MD 20705-2350
3. Spatial Sciences Laboratory; 1500 Research Plaza, Office 221E, Texas A&M University; College Station TX 77845