Gaya APA

Powers, R, B. (1993). Petroleum Exploration Plays and Resource Estimates, 1989 Onshore United States: Region 1, Alaska, Region 2, Pacific Coast (1). America AS: U.S. Geological Survey Bulletin 2034-A.

Gaya MLA

Powers, Richard, B.. "Petroleum Exploration Plays and Resource Estimates, 1989 Onshore United States: Region 1, Alaska, Region 2, Pacific Coast". 1 America AS: U.S. Geological Survey Bulletin 2034-A, 1993. Text.