The data on energy production from fossil fuels provided by The Shift Data Portal is based on the following sources:
· For the period 1900-1980: Bouda Etemad and Jean Luciani, World Energy Production 1900 – 1985, ISBN 2-600-56007-6, Data digitalized and published with agreement of B. Etemad.
· For the period 1980-2016: U.S. Energy Information Administration, Historical Statistics for 1980-2016, accessed on 2019-06-05.