McCoubrey, Hilaire
Brookfield Dartmouth , 1995
Buku Teks
Woodham, Jonatham M.
Oxford University Press, 1997
Buku Teks
edited by Jack A. Goldstone, Ted Robert Gurr, Farrokh Moshiri
Westview Press, 1991
Buku Teks
Black, C.E.
Alfred A. Knopf, 1961
Buku Teks
Varga, Eugen, 1879-1964
Foreign Languages Publishing House, 1961
Buku Teks