edited by Ian Qusby
Cambridge University Press, 1988
Buku Referensi
edited by A.W. Ward and A.R. Waller
Macmillan, 1939
Buku Teks
Peters, Pam
Cambridge University Press, 2006
Buku Referensi
Sampson, George
University Press, 1949
Buku Referensi
Sampson, George
University Press, 1959
Buku Teks