O`Neill, John, author
Routledge, 1993
Buku Teks
Butzer, Karl W., author
Cambridge University Press, 1982
Buku Teks
Macfadyen, A.
Pitman Publishing Corporation, 1963
Buku Teks
Boughey, Arthur S., author
McMillan Publisher, 1975
Buku Teks
Kendeigh, S. Charles
Prentice-Hall, 1975
Buku Teks