Notgeld of Nürnberg-Fürther Strassenbahn

Hello guys, or Herzlich Willkommen, rather,

I have purchased a wonderful set of notgeld from Nürnberg, these are  basically these 45 coins:https://en.numista.com/catalogue/index.php?r=n%FCrnberg-f%FCrther&c=&cc=y&cn=y&cj=y&ce=y&cu=y&cat=y&mode=simplifie&p=1&e=&d=&km=&i=&v=&m=&a=&t=&dg=&w=&g=

Lovely surprise, I have received it in this folder:

The coins are lovely presented and aligned in UNC quality, like this:


NOW, my question is: what is the year of mintage, my auctioner claims it is 1920, Numista has ND next to the coins, so anyone? - maybe with better Deutsch than I have, can you trace when these beauties were minted?

P.S. 1:   it is notgeld, but in such a quality of design that most of the current nations shall envy!!!

P.S.  2: It has a certificate as well, saying:

"Nachdruck verboten.
Verlag Hans Biegerl, Nürnberg, Roonstrasse 15. Telefon 7555
Preis 30 Pfennig"

- so I bet even the packing is close to contemporary...

This has been the only reference to any mintage date that I have come across: (as translated by Google)

The best known representatives of the Fürth emergency money should the octagonal aluminum motif trademarks of Nuremberg-Fürth tram with 20 Pfennig be and spare coins of Ludwig Railway 100, 150 and 200 pennies of the 1921st

1921 indeed
http://www.sixbid.com/browse.html?auction=366&category=6621&lot=322622

- they were made from 1917 until the company had to close in 1923
- the later issues like many other Notgeld coins were made for souvenir purposes
- a complete set is about 100€

that's all I know.

Well, thanks everyone, we still do not have a credible source for mintage years, though.

If it usually sells for EUR 100.00, then I am happy.
I have forked out almost EUR 42.00 for the entire pack with package and certificate letter.