Chancellor , 2001
Buku Referensi
Lye, Keith, author
The Royal Geographical Society, 2000
Buku Referensi
Rohkamm, Reinhard, author
Thieme, 2014
Buku Teks
C. S. Hammond and Company
C.S. Hammond & Co., [date of publication not identified]
Buku Teks
C.S. Hammond , 1961
Buku Referensi