<a href="https://nl.wikipedia.org/wiki/Anton_Mensing" class="extiw" title="nl:Anton Mensing">Antonius Wilhelmus Mari Mensing</a> (1866-1936)
Unknown photographer
<p>Early 20th century picture. The picture is known to be published in: 
</p>
<ul><li><i>Journal of the history of collections</i> 7 (1995) 236 ; named in J. Storm van Leeuwen (2013) as source. Describes picture as "Mensing in 1935"</li>
<li><a href="https://nl.wikipedia.org/wiki/Jan_Storm_van_Leeuwen" class="extiw" title="nl:Jan Storm van Leeuwen">Jan Storm van Leeuwen</a>, "A.W.M. Mensing antiquaar en veilinghouder 1866-1936," in: <i>Verzamelaars en verzamelingen. Koninklijke Bibliotheek 1798-1998.</i> Zwolle, 1998, p. 150-154.</li>
<li>J. Storm van Leeuwen, "<a rel="nofollow" class="external text" href="http://resources.huygens.knaw.nl/bwn1880-2000/lemmata/bwn1/mensing">Mensing, Antonius Wilhelmus Mari (1866-1936)</a>", in <i>Biografisch Woordenboek van Nederland</i>, 12-11-2013 ;</li></ul>