Coughlan, Robert, author
Time Incorporated, 1962
Buku Teks
Wallace, Alfred Russel, 1823-1913, author
Cambridge University Press, 2013
Buku Teks
Salmon, Cleveland
John Wiley & Sons, 1999
Buku Teks
World Health Organization, [date of publication not identified]
Buku Teks
Manson-Bahr, P.E.C.
Bailliere Tindall , 1982
Buku Teks