Gettell, Raymond G.
Appleton-Century-Crofts, 1928
Buku Teks
Grande, Sandy, 1964-
Rowman and Littlefield, 2015
Buku Teks
Mason, Alpheus Thomas,1899-1989
Prentice-Hall, 1959
Buku Teks
Mason, Alpheus Thomas,1899-1989
Cornel University Press, 1955
Buku Teks
edited by Nelson Lichtenstein
University of Pennsylvania press, 2006
Buku Teks