Aaron, Henry J., author
Brookings Institution, 1991
Buku Teks
edited by Stephen J. Williams
John Wiley & Sons, 1980
Buku Teks
Birenbaum, Arnold, author
Allanheld, Osmun, 1981
Buku Teks
edited by J. Timothy Harrington and Eric D. Newman
Springer, 2012
eBooks
Institute for Contemporary Studies, 1980
Buku Teks