James, yes without doubt period reference is the best, just looking at the 2nd advert again helps me determine what I had always thought about this particular Dula and the markings on the rear,
The advert states these knives were
Das Gebrauchsmesser des Forst-beamten

"HFB"
Heer Forst beamten

I'd always thought the chequered grips on this piece were specially ordered at the time.

Thanks

Gary

F Dula markings 002 (Custom).jpg (108.83 KB, 520 downloads)
Dula1asm.jpg (117.45 KB, 521 downloads)