Portrait of Ludwig Boltzmann, from 1855 to 1900.
<bdi><a href="https://www.wikidata.org/wiki/Q22115931" class="extiw" title="d:Q22115931"><span title="photographer (1832-1905)">Nikolaus Stockmann</span></a>
</bdi>
from 1855 to 1900
Archivio storico dell'Accademia delle Scienze - <a rel="nofollow" class="external text" href="https://www.accademiadellescienze.it/accademia/soci/ludwig-boltzmann">Catalogo digitale</a>