Jones, Len
Cambridge University Press, 1993
Buku Teks
Edwards, Rodney
McGraw-Hill, 1991
Buku Teks
Barker, Forrest, author
Prentice-Hall, 1989
Buku Teks
Mitchell, F. H., author
Addison-Wesley, 1959
Buku Teks
Watson, John, author
Macmillan, 1990
Buku Teks