edited by Joseph S. Roucek
Littlefield, Adams , !964
Buku Teks
edited David Marsh and Gerry Stoker
Macmillan, 1995
Buku Teks
Dyke, Vernon van, author
Stanford University Press, 1962
Buku Teks
Apter, David E., author
Winthrop, 1977
Buku Teks
Grimes, Alan P., author
Oxford University Press , 1959
Buku Teks