Glass, Jacqueline, author
Wiley-Academy, 2002
Buku Referensi
Curl, James Stevens, author
Donhead, 1992
Buku Referensi
edited by Paul Oliver
Cambridge University Press, 1998
Buku Referensi
Emmitt, stephen, author
Wiley-Blackwell, 2012
Buku Teks
Cowan, Henry J., author
E&FN Spon, 1998
Buku Teks