libkdtree++, a C++ template KD-Tree sorting container. OpenMS carries a modified copy of it
in src/openms/include/OpenMS/DATASTRUCTURES/KDTree.h, whose parts carry this notice:

  libkdtree++ is (c) 2004-2007 Martin F. Krafft <libkdtree@pobox.madduck.net>
  and Sylvain Bougerel <sylvain.bougerel.devel@gmail.com> distributed under the
  terms of the Artistic License 2.0.

  THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
  WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES
  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

The Artistic License 2.0 is in Artistic-2.0.txt, next to this file. The source code of the
modified copy is part of the OpenMS source code (https://github.com/OpenMS/OpenMS).
