Gagey, Edmond M., author
Columbia University Press, 1948
Buku Teks
Nannes, Caspar H,
The Catholic University, 1960
Buku Teks
Weales, Gerald Clifford, 1925-, author
Macmillan, 1969
Buku Teks
Miller, Jordan Y.
McGraw-Hill Book Company, Inc., 1961
Buku Teks
Lindsay, Howard
Random House, 1946
Buku Teks