Literature

[KAGGR#1]

Also a very good book for a quick overview is the Field guide from James Turinetti.
He wrote also a Buyers Guide with average prices for helmets (updated every 2 years), but unfortunately the last one was published for the years 2018-2020.

I have some of Jim's books and I know him
and see him each year at the S O S
my favorite is the one that he did on miters
Steve