This refencence documentation contains:

  <!--
    Copyright © 2009, 2010 Christian Persch

    Permission is granted to copy, distribute and/or modify this document
    under the terms of the GNU Free Documentation License, Version 1.2
    or (at your option) any later version published by the Free Software Foundation;
    with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts.

    A copy of the license is included in the COPYING.DOC file.
    -->

but no actual COPYING.DOC and also

    <legalnotice>
      <para>
        Permission is granted to copy, distribute and/or modify this document
        under the terms of the <citetitle>GNU Lesser General Public Licence</citetitle>, Version 2.1
        or (at your option) any later version published by the Free Software Foundation.

        You may obtain a copy of the <citetitle>GNU Lesser General Public Licence</citetitle>
        from the Free Software Foundation at
        <ulink type="http" url="http://www.gnu.org/licences/">GNU Licences web site</ulink>
        or by writing to:

        <address>
          The Free Software Foundation, Inc.,
          <street>51 Franklin St</street> – Fifth Floor,
          <city>Boston</city>, <state>MA</state> <postcode>02110-1301</postcode>,
          <country>USA</country>
        </address>
      </para>
    </legalnotice>



If the comment about the GFDL is no longer valid, please consider removing that section.