edited by Robert Moore Fisher
Doubleday, 1955
Buku Teks
Jarvis, Helen, author
Prentice-Hall, 2001
Buku Teks
Lang, Robert E., author
Brookings Institution Press, 2003
Buku Teks
Dore, R.P., author
University of California Press , 1958
Buku Teks
Warner, W. Lloyd, author
Yale University Press, 1955
Buku Teks