Barnard, David T.
Wm. C. Brown Publisher, 1988
Buku Teks
Blackwell Publishers, 2000
Buku Teks
Cambridge University Press, 1990
Buku Referensi
Deva, B. C.
National Book Trust, 1977
Buku Teks
Churchill, Winston, Sir, 1874-1965, author
Houghton Miffiln, 1951
Buku Teks