edited by Peter Burke
Pennsylvania State University Press, 1995
Buku Teks
Fedrizzi, Mariann
South Western Cengage Learning, 2011
Buku Teks
Longman , 1999
Buku Teks
MIT Press, 1977
Buku Teks
Pfitzer, Gregory M.
Northeastern University Press, 1991
Buku Teks