Here is an example of a 20 Mark from the Principality of Lippe, which definitely should be in the German States listing;
https://en.numista.com/catalogue/note226495.html .
The State Bank of the Principality of Lippe was an official issuer of one of the monarchies in Germany under the 1871 - 1918 German Empire.
Prince Leopold IV was the ruler when this 20 Mark note was issued.
https://en.wikipedia.org/wiki/Leopold_IV,_Prince_of_Lippe .
Aidan.