Paul Bonatz, Stuttgarter Archtekt
<a rel="nofollow" class="external text" href="https://web.archive.org/web/20161026030222/http://www.panoramio.com/user/969909?with_photo_id=81046743">Richard Mayer</a>
CC BY 3.0
<a rel="nofollow" class="external free" href="https://web.archive.org/web/20161026030215/http://www.panoramio.com/photo/81046743">https://web.archive.org/web/20161026030215/http://www.panoramio.com/photo/81046743</a>