Houston, Brant
St. Martin Press, 1996
Buku Referensi
Clymo, R. S.
Cambridge University Press, 2014.
Buku Teks
Black, Geoff
London : Prentice Hall, 2001,
Buku Referensi
Black, Geoff
Prentice-Hall, 2002
Buku Referensi
Knox, Frank M.
McGraw-Hill, 1965
Buku Teks