Ice axe carabiner hole

A question for you old timers who can reference.

When was and by who, was the carabiner hole added to ice axes?

I believe, and I think I read somewhere that Cassin introduced it around the late 60's, but just can't prove it.

Why do I care?; there's a lot folks out there selling ice axes believing they are older than they really are, the thing is, you need a reference you can verify.

Mario

Hi Mario,

you ever figure out the answer?

Earliest I can find, MacInnes Massey ice axe. 1963.