<bdi><a href="https://en.wikipedia.org/wiki/en:Ludwig_Knaus" class="extiw" title="w:en:Ludwig Knaus"><span title="German artist (1829–1910)">Ludwig Knaus</span></a>
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<a rel="nofollow" class="external text" href="https://www.lempertz.com/de/kataloge/lot/1027-1/105-ludwig-knaus.html">Kunsthaus Lempertz, Köln, Auktion 1027, 26.03.2014, Lot 105</a>