Energy - "The growth of energy consumption and prices in the U.S.A., F.R.G., France, and the UK", 1950 - 1980, Box: 19, Folder: 19. Charles Heller papers, RH MS 314. University of Kansas. Kenneth Spencer Research Library. https://archives.lib.ku.edu/repositories/3/archival_objects/490496 Accessed February 26, 2025.