Burr, Nelson R.
Princeton University Press,, 1961
Buku Teks
Weber, Max, 1864-1920
Beacon Press , 1963
Buku Teks
Olmstead, Clifton E.
Prentice-Hall, 1960
Buku Teks
edited by James Ward Smith and A. Leland Jamison
Princeton University Press, 1961
Buku Teks
Thompson, Ian
Longman, 1965
Buku Teks