https://www.mappingthelives.org/bio/583aaf3c-81ec-4a7d-9f96-46887fdc5dfe
https://online-ofb.de/famreport.php?ofb=juden_nw&ID=I280290&lang=en
His story: Kochmann Berthold – Gedenkbuch (gedenkbuch-duesseldorf.de)