Windrow, Martin, author
Grange Books, 2000
Buku Referensi
Grenville, J.A.S., author
Routledge, 2005
Buku Teks
Kotter, John P., 1947-, author
Free Press, 1997
Buku Teks
Brown, Neville, author
Pan Books, 1970
Buku Teks
Spencer, Frank, author
Pan Books, 1967
Buku Teks