Appendix
Twenty-seven companies were initially notified of a requirement to file Form EIA-28 (Financial Reporting System). This group was initially chosen from the top 50 publicly owned U.S. crude oil producers, in 1976, who had at least 1 percent of either the production or the reserves of oil, gas, coal, or uranium in the United States or 1 percent of refining capacity or petroleum product sales in the United States. The list of companies required to report was updated for mergers, acquisitions, and spinoffs which, together with the selection criteria applied to 1991 data, resulted in the list of companies shown in the tabulation on the following page.