Neustadt, Richard E., author
The Free Press, 1990
Buku Teks
Neustadt, Richard E., author
John Wiley & Sons, 1961
Buku Teks
Edwards, George C., author
Thomson, 2006
Buku Teks
Edwards, George C., author
Thomson Wadworth, 2006
Buku Teks
Ludwig, Emil, 1881-1948, author
Garden City Publishing, 1941
Buku Teks