Gonzalez, Andrew B.
Oxford University Press, 1984
Buku Teks SO
Singapore : The SEAMEO Regional English Language Centre
Majalah, Jurnal, Buletin
Richards, Jack C.
Cambridge University Press, 2015
Buku Teks
edited by Aris Ananta, Armin Bauer, Myo Thant
Institute of South East Asia Studies, 2013
eBooks
University of British Columbia Press, 1982
Buku Teks