I have completed the publication of all Frederick II the Great 3-Kreuzer issues on my website. The material includes date listings, recognized varieties, and documented die differences observed across the series.
A noteworthy detail concerns the 1779–1785 emissions from the Berlin mint, which were intended for Silesian circulation — a point that is not always clearly reflected in general catalogue descriptions.
Reference and documentation:
https://michalart.com.pl/