Gutteridge, Anne C.
Cambridge University Press, 1983
Buku Referensi
Lutz, William D., author
Cambridge University Press, 1994
Buku Referensi
Herkimer, Herbert
W.M. PennPublishing Corp., 1952
Buku Teks
edited by Geoffrey Parker
Cambridge University Press, 1995
Buku Referensi
edited by Michael Hoskin
Cambridge University Press, 1997
Buku Referensi