Penson, John B., author
Prentice-Hall, 1982
Buku Teks
Unger, Maurice A., author
Allyn and Bacon, 1969
Buku Teks
Bradley, Joseph F., author
Holt, Rinehart & Winston, 1957
Buku Teks
Pechman, Joseph A., author
Harvester Wheatsheaf, 1989
Buku Teks
Ward, Barbara, author
W.W. Norton, 1962
Buku Teks