Pease-Alvarez, Lucinda, author
Springer, 2012
eBooks
Farrell, Thomas S.C., author
Corwin Press, 2006
Buku Teks
Wells, Ronald A.
Mouton, 1973
Buku Teks
Parrot, Martin, author
Cambridge University Press, 2003
Buku Teks
Protherough, Robert
Open University Press, 1991
Buku Teks