Denhardt, Robert B., author
Thomson, 2009
Buku Teks
Denhardt, Robert B., author
Wadsworth and Cengage Learning, 2014
Buku Teks
Denhardt, Robert B., author
Harcourt College, 1999
Buku Teks
Herring, E. Pendleton, author
McGraw-Hill, 1936
Buku Teks
Simon, Herbert A., author
Alfred A. Knopf, 1973
Buku Teks