Kershaw, Joseph A.
Brookings Institution, 1970
Buku Teks
Perlman, Richard, author
McGraw-Hill , 1976
Buku Teks
Cambridge University Press, 2016
eBooks
United States Information Agency, 1987
Buku Teks
Chase, Richard B., author
A Signet Key Book, 1963
Buku Teks