Clapham, John, Sir, author
The Cambridge University Press, 1949
Buku Teks
edited by Robert Burchfield
Cambridge University Press, 1994
Buku Referensi
edited by Boris Ford
Cambridge University , 1992
Buku Teks
Gregg, Pauline, author
George G. Harrap, 1952
Buku Teks
Cambridge University Press, 2017
Buku Teks