The following files in this directory are licensed under CC BY 3.0 (https://creativecommons.org/licenses/by/3.0/):

1. .ogg versions of files made by Mike Koenig:
    * bell_siren.ogg - https://soundbible.com/1531-Temple-Bell.html
    * woop_siren.ogg - https://soundbible.com/1377-Woop-Woop.html