Fox, James R., author
Oceana Publication, 1992
Buku Referensi
Nobes, Christopher, author
Prentice-Hall, 1998
Buku Teks
edited by Christopher Nobes and Robert Parker
St. Martin`s Press, 1985
Buku Teks
edited by Christopher Nobes and Robert Parker
Prentice-Hall, 2004
Buku Teks
edited by Christopher Nobes and Robert Parker
Prentice-Hall, 1991
Buku Teks