Gaya APA
Johnston, D, A. (1981).
Guides to Some Volcanic Terranes in Washington, Idaho, Oregon, and Northern California .
Alexandria:
U.S.Geological Survey.
Gaya MLA
Johnston, David, A..
"Guides to Some Volcanic Terranes in Washington, Idaho, Oregon, and Northern California".
Alexandria:
U.S.Geological Survey,
1981.
Text.