Cook, Chris
Longman, 1991
Buku Referensi
edited by Ian Gregory, Don DeBats and Don Lafreniere
Routledge, 2018
Buku Teks
Palmer, Robert Roswell, 1909-2002
McGraw-Hill, 1992
Buku Teks
edited by Catherine Spooner, Emma McEvoy
Routledge, 2007
Buku Teks
edited by Simon Malpas, Paul Wake
Routledge, 2006
Buku Teks