Derived from

HefterLocher.wav by Mortifreshman
http://freesound.org/people/Mortifreshman/sounds/246518/
http://creativecommons.org/publicdomain/zero/1.0/

typewriter-olivetti-lettra-22.wav by keithpeter
http://freesound.org/people/keithpeter/sounds/123344/
http://creativecommons.org/publicdomain/zero/1.0/