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A. A. Production Inc.
ABB Vetco Gray Inc.
ABN-Amro Bank
Acadian Gas Pipeline System
Accell Natural Gas Co.
Act Operating Co.
Addison Energy Inc.
Advantage Energy Services Ltd.
AEDC U.S.A. Inc.
Aeon Energy Corp
AES Electric Limited
Agrium Inc.
Air Products and Chemicals Inc.
Alamo Resources LLC.
Alarado Resources
Albans Energy
Alberta Natural Gas Co. Ltd.
Alberta Resources Venture Inc.
Albrecht & Associates Inc.
Alet Inc.
Algonquin Petroleum Corp.
Allegro Operating Inc.
Alliance Resources PLC.
Allied Natural Gas Corp.
Alpandra Corp.
Alpha Land Services
Alpine Resources Inc.
Alsask Energy Services Inc.
Alta Mesa Resources Inc.
Alvarado, Smith, Villa & Sanchez
Amarado Oil Co. Inc.
Amegy Bank
Amerac Energy Corp.
American Coastal Energy
American Energy Partners
American International Petroleum
American Oil & Gas Inc.
American Penn Energy Inc.
American Refining and Exploration
American Trading and Production
Ameriwest Energy Corp.
Amni International Petroleum Development
Ample Resources
Anadarko Petroleum Corp.
Anderman Operating Co. Inc.
Andex Resources LLC.
Anglo Suisse Inc.
Antara Resources Inc.
Antrim Energy Inc.
Apache Corp.
Apex Oil & Gas Inc.
Aquila Energy Capital Corp.
Arawak Energy Corp.
Arc Resources Ltd.
Arcapita Bank BSC.
Archean Energy Ltd.
Arco Oil & Gas Co.
Arena Energy
Argonauts Group Ltd.
Arjon Enterprizes Ltd.
Armstrong Oil & Gas Inc.
Arrow Exploration Co.
Arthur Smith Corp.
Ascom Group S.A.
Asher Associates Inc.
Asociacion SMC-Pacifpetrol Santa
Aspen Energy Corp.
Atco Electric
Atlantic LNG Co. of Trinidad
Auburn Enterprises
Aurora Gas LLC.
Avalanche Energy Ltd.
Aviara Energy Corp.
Axem Resources Inc.
A/D Holdings LP.
Aberdeen Petroleum (USA) Inc.
Abu Dhabi National Oil Co.
Acadian Resource Co.
Acon Investments
Adams Resources Exploration Corp.
Adobe Energy Inc.
AEC Oil & Gas
Aegis Energy Inc.
Aera Energy LLC..
Agip Petroleum Co. Inc.
AIG Energy Inc.
Alabma Electric Cooperative Inc.
Alamo-Palace MP 59 LLC.
Alaska Oil & Gas Conservation
Alberta Ltd.
Alberta Oil Sands Inc.
Alberta Special Waste Management
Alcoa / Alumax
Alexander Energy Corp.
All American Oil & Gas Inc.
Alliance Energy Corp.
Allied Energy Corp.
Almeida Partners Ltd.
Alpar Resources Inc.
Alpine Resources Inc.
Alrosa
Alta Energy Corp.
Alumax Inc.
Amalgamated Explorations Inc.
Amaranth Advisors
Amen Properties
American Appraisal Associates Inc.
American Energy Operations Inc.
American Exploration Co.
American Liberty Oil Co.
American Oil Services
American Premier Underwriters Inc.
American Resources Offshore Inc.
American West Oil and Gas Corp.
Aminex USA Inc.
Amoco Production Co.
Amvest Oil & Gas Inc.
Ancell Energy Consulting Inc.
Anderson Oil Co.
Andrews & Kurth LLP.
Anshutz Exploration Corp.
Antero Resources Corp.
Aoco Operating Co. LLC.
Apco Argentina Inc.
APF Energy Inc.
Aquila Energy Resources
Arbol Resources Inc.
Arcadia Exploration and Prodcution
Arch Petroleum Inc.
Archer Resources Ltd.
Arctic Slope Regional Corp.
Arg Resources Inc.
Aries Resources LLC.
Arlington Energy Partners
Arpetrol Inc.
Arroyo Energy Investors
Arxa International Energy Inc.
Asgard Resources Ltd.
Ashland Exploration Inc.
Aspect Resources LLC.
AT&T Capital
Athena Energy LLC.
ATP Oil & Gas Corp.
Aures Energy LLC.
Autry C. Stephens
Avatar Petroleum Inc.
Aviva Petroleum Inc.