1. Resources and Man;Hubbert,1969
2. Future petroleum producing capacity of the United States;Zapp;U.S. Geol. Survey Bull. 1142H,1962
3. Energy Resources;Hubbert;Nat. Acad. Sci. Pub. 1000-D,1962
4. Degree of advancement of petroleum exploration in the United States of America;Hubbert;Assoc. Pet. Geol. Bull.,1967
5. Where will energy come from in 2059;Weeks;Pet. Engineer,1959