Freeman, Joseph
Victor Gollancz, 1938
Buku Teks
Balbus, Isaac D.
Russell Sage Foundation, 1973
Buku Teks
Sheehan, Paul, author
Cambridge University Press, 2010
eBooks
Hough, Graham, author
Barnes & Noble, 1961
Buku Teks
Patterson, Thomas E., author
McGraw-Hill, 203
Buku Teks