Benoit, Emile
Columbia University Press, 1962
Buku Teks
Humphrey, Don D., author
Frederick A. Praeger , 1962
Buku Teks
Stanford Research Institue, 1960
Buku Teks
Dean, Vera Micheles
Alfred.A.Knopf, 1950
Buku Teks
League of Women Voters of the United States 1961, 1962
Buku Teks