Enzmann, Dieter R.
Raven, 1984
Buku Teks
McGovern, William M., author
University of North Carolina Press, 1939
Buku Teks
Danubian Press,, 1970
Buku Teks
Wilson, Peter H., author
Routledge, 2000
Buku Teks
Chandavarkar, Anand G., author
St. Martin`s Press, 1996
Buku Teks