Pelz, Ruth.
Murray Pub. Co, 1979
Buku Teks
Love, Edmund G
Harper & Row , 1963
Buku Teks
Ferling, John, author
Oxford University Press, 2003
Buku Teks
Roosevelt, Eleanor, author
Harper & Brothers, 1949
Buku Teks
Ferrell, Robert H., author
W.W. Norton, 1959
Buku Teks