Hadden, Susan G.
Westview Press, 1989
Buku Teks
Cross, Harold L.
Columbia University Press, 1953
Buku Teks
Isaacs, Asher, 1902-1963, author
Van Nostrand , 1964
Buku Teks
Pierce, Lawrence C., author
Goodyear, 1971
Buku Teks
Shepherd, William G., author
Richard D. Irwin, 1979
Buku Teks