Echols, John M., author
Gramedia, 1992
Buku Referensi
Harper Collins Publisher, 1994
Buku Referensi
Lea, Christine
New York: Oxford University Press, 1993,
Buku Referensi
Steingass, F., author
Gaurav Publishing House, 1986
Buku Referensi
Aksara Binacendekia, 1990
Buku Referensi