"Spy pictures of suffragettes revealed". BBC, 3 October 2003: For an in-depth British history see: Bunyan, Tony. The Political Police in Britain. Quartet Books, 1977.
Metropolitan Museum of Modern Art – "Strand set out for Five Points, the heart of the immigrant slums on the Lower East Side, with his camera rigged with a false lens to distract attention. Approaching a potential subject, Strand turned ninety degrees away and aimed the false lens in the direction he was facing. The real lens, on an extended bellows, stuck out under his arm toward the person ..."
