Plumb, J.H.
The British Council by Longmans, Green, 1971
Buku Teks
Mallaby, George
Leo Cooper, 1972
Buku Teks
Ranke, Leopold von, 1795-1886, author
Roskam, 1944
Buku Teks
edited by Leslie Stephen, Sidney Lee
Oxford University Press, 1950
Buku Referensi
Hyman, Anthony
Oxford University Press, 1982
Buku Teks