Ashley, Maurice, author
Penguin Books, 1952
Buku Teks
Stroud, Angus, author
Routledge, 1999
Buku Teks
Firth, Charles Harding, author
G.P. Putnams Sons, 1928
Buku Teks
Plumb, J.H. (John Harold), 1911-, author
Penguin Books, 1963
Buku Teks
Thomas, David, author
Penguin Books, 1963
Buku Teks