Times Books, 1991
Buku Referensi
edited by Sam Smiles and Stephanie Moser
Blackwell Publishing, 2005
Buku Teks
Shanks, Michael, author
Routledge , 1992
Buku Teks
Stiebing, William H.
Oxford University Press, 1993
Buku Teks
edited by Peter G. Stone, Robert MacKenzie
Routledge, 1994
Buku Teks