Friedmann, Julian, author
Intellect, 2000
Buku Teks
Kamerschen, David R., author
South-Western Publishing, 1992
Buku Teks
Chandler, Lester Vernon, 1905-, author
Harper & Row , 1959-1973
Buku Teks
Hart, Albert Gailord, 1909-, author
Prentice-Hall, 1961
Buku Teks
Auerbach, Robert D., author
Macmillan, 1989
Buku Teks