Mainka (<a href="https://de.wikipedia.org/wiki/Carl_Mainka" class="extiw" title="de:Carl Mainka">de</a>) at the First General Assembly of the International Seismological Association in The Hague 1907, courtesy of GeoForschungsZentrum (GFZ), Potsdam.
Unknown author<span style="display: none;">Unknown author</span>
<a rel="nofollow" class="external text" href="https://hgss.copernicus.org/articles/10/173/2019/hgss-10-173-2019-f03-high-res.jpg">GeoForschungsZentrum (GFZ), Potsdam.</a>