Valkenier, Elizabeth Kridl, author
Frederick A. Praeger, 1983
Buku Teks
Spector, Ivar
Universtity of Washington Press, 1958
Buku Teks
Saivetz, Carol R.
Westview Press, 1985
Buku Teks
Pergamon Press, 1980
Buku Teks
Thornton, Thomas Perry
Princeton University Press , 1964
Buku Teks