data/sliding-1.ogg
data/sliding-n.ogg
    distributed under GPL v. 3 or later (see COPYING)
    originated from Wildfire Games’ data of 0 A.D. (under GPL v. 2 or later)
    originally named “ui_button_click.ogg” and “ui_button_longclick.ogg”
    see http://trac.wildfiregames.com/browser/ps/trunk/binaries/data/mods/mod/audio/interface/ui?order=name

data/gameover.ogg
    distributed under GPL v. 3 or later (see COPYING)
    originated from GNOME games (under GPL v. 2 or later)
