Schiffman, Harold F.
Routledge, 1996
Buku Teks
Ahearn, Laura M. author
John Wiley & Sons, Incorporated,, 2016
Buku Teks SO
edited by Alessandro Duranti
Blackwell Publishing, 2006
Buku Teks SO
Cambridge University Press, 2009
eBooks
Sandler, Wendy
Cambridge University Press, 2006
Buku Teks