Lambert, Wallace E., author
Stanford University press, 1972
Buku Teks
edited by Howard Giles and W. Peter Robinson
John Wiley & Sons, 1990
Buku Referensi
Devito, Joseph A., author
Random House, 1970
Buku Teks
edited by Ruth M. Kempson
Cambridge University Press , 1990
Buku Teks
Cambridge University Press, 1994
Buku Teks