Rand McNally, [date of publication not identified]
Buku Referensi
Donnelly, Thomas C.
The University of New mexico Press, 1953
Buku Teks
Dullemen, Inez van
Querido, 1988
Buku Teks
Vaillant, George C.
Penguin Books, 1944
Buku Teks
Grayson, George W.
Thomson, 2004
Buku Teks