<bdi><a href="https://en.wikipedia.org/wiki/en:Adolf_Humborg" class="extiw" title="w:en:Adolf Humborg"><span title="Austrian painter (1847-1921)">Adolf Humborg</span></a>
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1. <a rel="nofollow" class="external text" href="http://www.arcadja.com/auctions/en/humborg_adolf/artist/14125/">William Doyle, New York, 7.6.2006, lot 2007 via Arcadia auction results</a><br>2. <a rel="nofollow" class="external text" href="https://www.lotsearch.de/user/login?paywall=1&amp;redirect=/artist/adolf-humborg/archive">William Doyle, New York, 7.6.2006, lot 2007 via Lotsearch</a>