Cobban, Alfred
Penguin Books, 1990
Buku Teks
Hoffding, Harold
Dover, 1955
Buku Teks
Guerard, ALbert
Ann Arbor The University of Michigan 1959
Buku Teks
Cobban, Alfred
[publisher not identified], [date of publication no identified]
Buku Teks
Hauser, Arnold
Alfred A. Knopf , 1952
Buku Teks