1. Nuclear energy and the fossil fuels: drilling and production practice;Hubbert;Am. Petrol. Inst.,1956
2. M.K. Hubbert and D.H. Root, in S.P. Parker (Ed.), Outlook for Fuel Reserves, McGraw-Hill Encyclopedia of Energy, 2nd edn., McGraw-Hill, New York, Vol. 19, p. 45.
3. Energy resources: a report to the committee on natural resources;Hubbert,1962