Harbaugh, John W., and Michel Ducastaing. “Historical Changes in Oil-Field Populations As a Method of Forecasting Field Sizes of Undiscovered Populations: A Comparison of Kansas, Wyoming, and California”. Bulletin (Kansas Geological Survey), Jan. 1981, pp. 1-56, https://doi.org/10.17161/kgsbulletin.no. 23609.