APA

Ulmishek G. F., Geological Survey, World Petroleum Congress (13th. : 1991 : Buenos Aires) & Geological Survey.Areal and spatial distribution and effectiveness of the world's petroleum source rocks. : .

Chicago

Ulmishek Gregory F, Geological Survey, World Petroleum Congress (13th. : 1991 : Buenos Aires) and Geological Survey.Areal and spatial distribution and effectiveness of the world's petroleum source rocks. : .

Harvard

Ulmishek G. F., Geological Survey, World Petroleum Congress (13th. : 1991 : Buenos Aires) and Geological Survey.Areal and spatial distribution and effectiveness of the world's petroleum source rocks. : .

MLA

Ulmishek Gregory F, Geological Survey, World Petroleum Congress (13th. : 1991 : Buenos Aires) and Geological Survey.: . .