I'm looking for the frequencies of all Area Control Centers (ACC) in Germany. What are they, or where are they published?
The radio frequencies used by German ACC sectors are listed in AIP Germany ENR 2.1 (page 36 onward). This is the standard place to find ACC frequencies for any country in the world.
There are too many frequencies to list here, but you can find the full document here. Below is a screenshot of page 36. Column 1 contains the sector name and dimension, column 4 contains the frequency(ies) used by that sector.
Okey I found it out. The map of Germany ACC sectors you can find here: https://www.eurocontrol.int/sites/default/files/content/documents/nm/cartography/erc09l-23may2019.pdf If you have your airway and name of sectors, then you are able to find the frequency on this site: http://www.aviascan.de/downloads/Sector%20Information%20Manual%20Germany.pdf