Petroleum and natural gas bibliography / Being the result of an effort to compile and classify the items of literature in English for which copyrights have been issued, but including many other published items which have been catalogued by the Library of Congress, as well as a few items of general interest not found in the Library of Congress, all of which fall within a comprehensive definition of book literature, as distinguished from periodical literature ... but including ... references to all articles, notes and comments relating to petroleum and natural gas appearing in the legal periodicals published in the United States. By Robert E. Hardwicke.