prepared by the Special Publications Division, National Geographic Society, Washington, D.C.
The National Geogarphic Society, 1986
Buku Referensi
Arnold, Dieter, author
Princeton University Press, 2003
Buku Referensi
Bone, Robert G., author
Littlefield, Adam, 1957
Buku Teks
edited by John Miksic
Archipelago Press, [date of publication not identified]
Buku Teks
Maine, Henry Sumner, 1822-1888, author
Everyman's Library, 1972
Buku Teks