Smith, Jennifer, author
Macmillan, 1982
Buku Teks
Korea Foundation
Cookand/Besthome, 2003
Buku Teks
Peters, Pam, author
Cambridge University Press, 2006
Buku Referensi
Geoffrey, Leech N., author
Longmans, 1993
Buku Teks
Mitchell, Bruce, author
Blackwell, 1995
Buku Teks