edited by Valerie Kinsella
Cambridge Uniiversity Press , 1979
Buku Teks
Roulet, Eddy
Longman, 1979
Buku Teks
Gebhard, Jerry G.
Cambridge University Press, 1999
Buku Teks
Richards, Jack C.
Cambridge University Press, 1994
Buku Teks
Mackey, William Francis
Longman, 1978
Buku Teks