You asked for websites to search:
you can search lots of historical dutch newspapers. It is possible to search for a name e.g. Carl near Chasler. Don't give up fast, the software is not perfect (yet) and a small change to your query may give lots of hits. As an example I searched for Chasler near viool (= violin) and found he played at a meeting of the national union of clerks: http://kranten.kb.nl/view/article/id/ddd%3A010212891%3Ampeg2...
jewish nazi-victims can be found.
My tip is to search by birth date, because the spelling of names is variable.
An example: Bellina's brother Eduard and his family... http://www.joodsmonument.nl/person/503903/nl
Unfortanately many Chaslers can be found on this website as well.
Also do not forget to search the community and comments. More information may have been added.