Institute for Contemporary Studies, 1980
Buku Teks
Aaron, Henry J., author
Brookings Institution, 1991
Buku Teks
Hogue, Kathleen
Welker, 1988
Buku Teks
Somers, Herman Milles, author
Brookings Institution, 1962
Buku Teks
Dewar, Diane M.
Jones & Bartlett Learning, 2017
Buku Teks