edited by James Flood, Julie M. Jensen, Diane Lapp, James R. Squire
Macmillan, 1991
Buku Referensi
Sambrook, G.A.
Longmans, Green, 1947
Buku Teks
London Collier-Macmillan 1965,
Buku Teks
Newby, Michael
Cambridge University Press, 1988
Buku Teks
Parrot, Martin
Cambridge University Press, 2003
Buku Teks