Grana, Sheryl J
Prentice-Hall, 1999
Buku Teks
Sendall, Jane, author
Oxford University press, 2014
Buku Teks
Smith, Jane
Headway , 1995
Buku Teks
Midgley, James, author
Sage Publications, 1997
Buku Teks
Tucker, W.T., author
Holt, Renehart and Winston, 1964
Buku Teks