Meyer, R.F., and Attanasi, E.D., 2003, Heavy oil and natural bitumen; strategic petroleum resources: U.S. Geological Survey Fact Sheet FS-070-03, 2 p.
http://pubs.usgs.gov/fs/fs070-03/
Meyer, R.F., Attanasi, E.D., and Freeman, P.A., 2007, Heavy oil and natural bitumen resources in geological basins of the world: U.S. Geological Survey Open-File Report 2007-1084, 42p.
http://pubs.usgs.gov/of/2007/1084/
3 online reference(s) found in Energy Publications Database.