Columbia subject headings:
Harvard subject headings:
Biographies.
Cryptographers--United States--Biography.
Cryptography--United States--History.
Friedman, Elizebeth, 1892-1980
Friedman, William F. (William Frederick), 1891-1969
Princeton subject headings:
Cryptographers--United States--Biography.
Cryptography--United States--History.
Friedman, Elizebeth, 1892-1980.