Webster, J.B.
Frederick A. Praeger, 1967
Buku Teks
Artikel Jurnal
Robertson, Priscilla
University Press, 1971
Buku Teks
Johnson, Chalmers, 1931-2010
Vakils, Feffer and Simons Private, 1966
Buku Teks
edited by Jack A. Goldstone, Ted Robert Gurr, Farrokh Moshiri
Westview Press, 1991
Buku Teks