Smith, F. (1971). Conservation in the United states: A documentary history. 5v. Van nostrand.
Chicago Edition CitationSmith, Frank. Conservation in the United States: A Documentary History. 5v. New york: Van nostrand, 1971.
Cita MLASmith, Frank. Conservation in the United States: A Documentary History. 5v. Van nostrand, 1971.
Atenció: Aquestes cites poden no estar 100% correctes.