Berlin : Mouton Publishers
Majalah, Jurnal, Buletin
edited by Trevor Harley
Sage, 2011
Buku Teks
Garman, Michael, author
Cambridge University Press, 1990
eBooks
Warren, Paul, 1958-, author
[Cambridge University Press, ], 2013
eBooks
Steinberg, Danny D., author
Longman, 1982
Buku Teks