Alexander, Robert J.
Macmillan, 1962
Buku Teks
Cypher, James M., author
Routledge, 1997
Buku Teks
Rao, V.K.R.V., author
Asia Publishing House, 1964
Buku Teks
Rostow, Walt Whitman, author
W.W. Norton, 1962
Buku Teks
The The University of Chicago
The University of Chicago Press, 1972
Buku Teks