Slesser, Henry
Stevens and Sons Limited, 1962
Buku Teks
Winfield, Percy Henry
Univercity Press, 1921
Buku Teks
Skegg, P. D. G., author
Oxford Clarendon Press , 1984
Buku Teks
Kiralfy, A.K.R.
Sewwt & Maxwell Limited, 1960
Buku Teks
Amery, L.S., author
Oxford University Press, 1953
Buku Teks