Lang, Theodore, author
Ronald Press, 1944
Buku Teks
Barfield, Jesse T., author
South-Western College Publishing, 1998
Buku Teks
Harris, Walter O., author
Public Administration Service, 1944
Buku Teks
Vance, Lawrence L., author
Henry Holt, 1959
Buku Teks
Sickle, Clarence L. van, author
Prentice-Hall, 1955
Buku Teks