1 October 2011 | Rotterdam

Museum Boijmans Van Beuningen in Rotterdam has created a web-portal on Provenance Research which, among other cases, contains a wealth of information about the Koenigs Collection, including claims by one of his many grandchildren. Visit the museum’s website. Here’s  a direct link to the section about the Koenigs Collection.

Bezoek de website voor de Nederlandse documenten betreffende het herkomstonderzoek van het museum en in het bijzonder de Collectie Koenigs
 
Through the many hyperlinks, found throughout the text and at the end of the 19 pages pdf-document, you may find dozens of documents with more detailed information.