A picture of David Keizer can be found in H. Beem, De verdwenen Mediene : mijmeringen over het vroegere Joodse leven in de provincie (Amstelveen 1982)
This person is commemorated on a memorial in Coevorden. More information on this memorial can be found (in Dutch) on the website of the Nationaal Co…
In addition, a Jokos file (number 54158) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.