Hoffman, Ross J.S.
Littlefield, Adams, 1958
Buku Teks
Hollister, C. Warren
John Wiley & Sons, 1968
Buku Teks
Rickard, J.A.
Barnes & Noble, 1952
Buku Teks
Scott, Jonathan F.
Appleton Century Croffs, 1933
Buku Teks
Hall, John W.
Yale University Press, 1974
Buku Teks