Columbia subject headings:
Harvard subject headings:
APL (Computer program language)
Babbage, Charles, 1791-1871.
Ciphers--History.
Cryptographers--Great Britain--Biography.
Cryptography--History.
Princeton subject headings:
APL (Computer program language)
Babbage, Charles, 1791-1871.
Ciphers--History.
Cryptographers--Great Britain--Biography.
Cryptography--History.