Wallace, Alfred Russel, 1823-1913, author
Cambridge University Press, 2013
Buku Teks
Coughlan, Robert, author
Time Incorporated, 1962
Buku Teks
Salmon, Cleveland, author
John Wiley & Sons, 1999
Buku Teks
World Health Organization, [date of publication not identified]
Buku Teks
Hyde, Richard, author
E & FN Spon, 2000
Buku Teks