<bdi><a href="https://www.wikidata.org/wiki/Q18611778" class="extiw" title="d:Q18611778"><span title="German painter (1824-1889), son of Caspar David Friedrich">Adolf Friedrich</span></a>
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<a rel="nofollow" class="external text" href="http://www.arcadja.com/auctions/de/private/friedrich_gustav_adolf/kunstwerken/10426/0/?rvn=3">Leo Spik, Berlin, 29.06.2017, lot 56 via ARCADJA auction results</a>