Deutsch, Karl Wolfgang, 1912-1992
Technology Press of the Massachusetts Institute of Technology, 1953
Buku Teks
Ward, Barbara
University of Toronto Press , 1963
Buku Teks
Gellner, Ernest
Cornell University Press, 2008
Buku Teks
Dutton., 1963.
Buku Teks
Kautsky, John H.
John Wiley & Sons, 1967
Buku Teks SO