Young, Robert, 1950-, author
John Wiley & Sons, 2015
Buku Teks
Williamson, J.A.
Macmillan, 1965
Buku Teks
Todorova, Elissaveta
Sofia press, 1987
Buku Teks
Grant, Michael
Routledge, 1999
Buku Teks
Christopher Bayly, editor
acts On File Book, 1989
Buku Referensi