Ladd, Carll Everett
W.W. Norton , 1987
Buku Teks
Little, Brown & Co., 1982
Buku Teks
Burns, James McGregor, author
Prentice-Hall, 1972
Buku Teks
Burns, James McGregor, author
Prentice-Hall, 1989
Buku Teks
OConnor, Karen, author
Addison Wesley Longman, 2001
Buku Teks