U.S. Department of Energy U.S. Department of Justice U.S. Internal Revenue Service UBS Investment Bank Ultramar Oil and Gas Ltd. Unexco Inc. Union Petroleum Co. Unit Corp. United Energy Group Ltd. United Natuional Group Universal Resources Corp. Unocal |
U.S. Department of Interior (MMS) U.S. Energy Corp. UB15 Petroecuador Ultra Petroleum Corp. UMC Petroleum Corp. UniCorp Inc. Unisource Energy Corp. Unit Drilling and Exploration Co. United Gas Holding Corp. United Utilities Corp. University of Texas System Ural Petroleum Corp. |