APA

Ahlbrandt T. S., Klett T. R., Pollastro R. M., World Petroleum Congress (15th. : 1997 : Beijing), Klett T. R. & Pollastro R. M.Estimates of undiscovered oil and gas in petroleum systems of the world. : .

Chicago

Ahlbrandt Thomas S, Klett Timothy R, Pollastro Richard M, World Petroleum Congress (15th. : 1997 : Beijing), Klett Timothy R and Pollastro Richard M.Estimates of undiscovered oil and gas in petroleum systems of the world. : .

Harvard

Ahlbrandt T. S., Klett T. R., Pollastro R. M., World Petroleum Congress (15th. : 1997 : Beijing), Klett T. R. and Pollastro R. M.Estimates of undiscovered oil and gas in petroleum systems of the world. : .

MLA

Ahlbrandt Thomas S, Klett Timothy R, Pollastro Richard M, World Petroleum Congress (15th. : 1997 : Beijing), Klett Timothy R and Pollastro Richard M.: . .