Plucknett, Theodore Frank Thomas
At The University Press, 1958
Buku Teks
Arnstein, Walter L.
Head, 1983
Buku Teks SO
Barker, Ernest, Sir, 1874-1960
Oxford University Press, 1942
Buku Teks SO
Himmelfarb, Gertrude
Weidenfeld and Nicolson,, 1968
Buku Teks SO
edited by Christopher Pawling
Macmillan, 1984
Buku Teks SO