Mathias, Peter
Methuen , 1979
Buku Teks
Madya Wisaksana, author
Fakultas Ilmu Pengetahuan dan Budaya Universitas Indonesia, 1996
UI - Skripsi (Membership)
Cronin, James E., author
Routledge, 1991
Buku Teks
edited by Tony Buxton, Paul Chapman and Paul Temple
Routledge , 1994
Buku Teks
Tomlinson, Jim, author
Methuen, 1981
Buku Teks