I think there is a lot of doubt surrounding these knifes ,
im not sure but i dont think any are shown in the books by angola/littlejohn or baker,
German daggers of ww2 vol2 does have a chapter regarding them and the authors rider regarding the authanticity of them, ive always wonderd why they are so scarce compared to the amount of Hjs on the market,
Hopefully Russ will know more...