Gimlette, John D., author
Oxford University Press, 1971
Buku Referensi
Agrawal, Giriraj Sharan, author
Diamond pocket books, 2001
Buku Referensi
Mawson, C. O. Sylvester, author
Garden City Publishing Company, 1940
Buku Referensi
Smith, Charles John, author
Bell and Sons, 1917
Buku Referensi
Lewis, Norman, author
Harper & Row , 1962
Buku Referensi