It is authentic.
I would suggest you leave it the way it is. If you clean it up, you will likely lose any real value in it.
Searching for anything relating to, Anton Boos, 934 Stamm. Kp. Pz. Erz. Abt. 7, 3 Kompanie, Panzer-Regiment 2, 16th Panzer-Division (My father)
Thank you for your quick and helpfull response.
Do you have a rough ballpark value? Im not going to sell but im really curious if i overpaid. How rare would a karl rob kaldenbach from 1938 be?