National Geographic Society, 1955
Buku Teks
edited by Thomas Biolsi
Blackwell Publishing, 2004
Buku Teks
Longstreet, Stephen.
Doubleday, 1970
Buku Teks
Vestal, Stanley, author
Random House, 1948
Buku Teks
Collier, John, 1884-1968, author
New American Library, 1947
Buku Teks