Humphries, Christopher J., author
Clarendon Press, 1986
Buku Teks
Brown, James H., author
Mosby, 1983
Buku Teks
Peilou, E.C.
John Wiley & Sons, 1979
Buku Teks
Huggett, Richard John
Routledge, 1998
Buku Referensi
Hengeveld, R.
Cambridge University Press, 1990
Buku Teks