Using the following links you can research online in the German National Library's catalogue of materials using the term "Heinz Mack" or "ZERO MACK". The search term "ZERO", on its own, provides a large number of results, which are unrelated to the art of the ZERO Group, in a great many cases.

• Research "Heinz Mack"https://portal.d-nb.de/opac.htm?method=simpleSearch&query=heinz+mack
• Research "ZERO"

A further research possibility is provided by the BAM portal for libraries,archives and museums. The abbreviation BAM stands for a joint Internet offering by libraries, archives and museums in Germany:

• Research "Heinz Mack"