Kidron, Michael
Simon & Schuster, 1984
Buku Teks
Lye, Keith
The Royal Geographical Society, 2000
Buku Referensi
Debenham, Frank
Reader's Digest Association, 1979
Buku Referensi
C. S. Hammond and Company
C.S. Hammond & Co., [date of publication not identified]
Buku Teks
C.S. Hammond , 1961
Buku Referensi