patent certificate Karl Spitzenberg Russia 1906
<a href="//commons.wikimedia.org/w/index.php?title=User:Bmontag&amp;action=edit&amp;redlink=1" class="new" title="User:Bmontag (page does not exist)">Bmontag</a>
2012-05-04
<span class="int-own-work" lang="en">Own work</span>