The archives and collections of the ADNG are housed at the office of the ADNG, the University of Groningen, and the Groninger Archives.
The search box on this page gives the titles of all the archives and collections managed by ADNG. The collections Behavioral/Performancelevel-tests, Image Bank, and Library are searchable at a record level (in Dutch).
The description of archives in keeping at the Groninger Archives contains a link to this archive. Clicking the link will take you directly to the site of the Groninger Archives. There you can search the archive at record level (in Dutch).