Are they WWII or WWI ?

I have some boot knives (marked 5 with sicky eagle, luftwaffe?) that have 3 clamps on the backside of the scabbard (most common in Norway) and blades are double edged. Are these WWII or WWI ? They are brought to Norway by germans during WWII.

Where can I find out more about german fighting knives and boot knives, any websites or books ?

Just ordered the book "Fighting knives" by Stephens, hope it will give me a lot of answers.

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Boot Knife