Need reference book or website for Karl Ens Porcelain Birds pre WWII

Does anybody know of a reference for the bird models produced by Karl Ens?
I have bought a bunch at a local collection auction and am trying to confirm bird names and rarity. They are mostly green windmill stamped which as far as I can tell is pre WWII.
Cheers
Stephen

 

https://www.replacements.com/webquote/co_knkmisf.htm
I haven’t checked dates. I’m sure someone will come along with more info. This should give you a start.
Cheers!

 

Thanks for that but they are not much help I'm afraid. Gee it's hard to find data on the models Ens produced. Kind off strange actually as there are lots around and they sell for a good price and seem quite popular but no one appears to have a website dedicated to Karl Ens work. Will keep looking.
Cheers
Stephen

 

You could post pictures.

 

Actually know the name of most of the birds from google images and eboo listings but I've got a figurine of an Egyptian girl that I can't track down. Was told third hand that the black variety was very rare.
Here she is. Only pic I've got at the moment.

 

What does the tag say?

 

Objet d'Art, Lot 47, Scammell Auctions, I think. Can't you zoom?

 

Oh ok, thank you. I thought it might have artists name.