World Health Organization, [date of publication not identified]
Buku Teks
Coughlan, Robert
Time Incorporated, 1962
Buku Teks
Manson-Bahr, P.E.C.
Bailliere Tindall , 1982
Buku Teks
Nick Beeching, Geoff Gill.
Wiley-Blackwell, 2014
Buku Teks
Wallace, Alfred Russel, 1823-1913
Cambridge University Press, 2013
Buku Teks