Ward, A.C.
The English Language Book, 1928
Buku Teks
Ewen, David, author
Prentice Hall, 1968
Buku Referensi
Ruthven, K.K., author
Cambridge University Press, 1979
Buku Teks
Korean Culture & Arts Foundation, 1984
Buku Teks
Thwaite, Anthony, author
Heineman, 1984
Buku Teks