Portrait of Alexander William Williamson, before 1904.
<bdi><a href="https://en.wikipedia.org/wiki/en:Herbert_Rose_Barraud" class="extiw" title="w:en:Herbert Rose Barraud"><span title="English photographer (1845-1896)">Herbert Rose Barraud</span></a>
</bdi>
Archivio storico dell'Accademia delle Scienze - <a rel="nofollow" class="external text" href="https://www.accademiadellescienze.it/accademia/soci/alexander-william-williamson">Catalogo digitale</a>