I think what you call "higher echelon" are just vulgarization books written by academics. A fun example is in physics, the "Feynman" literature. Because of all

I think what you call "higher echelon" are just vulgarization books written by academics. A fun example is in physics, the "Feynman" literature. Because of all the published stuff, you have only his lecture that are actually authored by him (and two co-authors, he was the speaker but by no mean the only expert involved). Lot of the books are just anaecdata or just people trying to remember discussion they had with him, and two are based on a biograph work, except he wasn't a biograph so in my country, he would probably have received pushback. The only feynman book i would call "higher echelon" are his published public lectures. Even his biography i would consider an "airport book" (interestingly enough, i have found that book at an airport 10 years ago while visiting the western US). Still, his biography is a hundred time better than random slop written (and now probably AI-hallucinated) about him by people who met him once, and is still very interesting.