Found 2 comments on HN
whack · 2017-02-17 · Original thread
I actually don't recall where I read that. It was one of the following 2 books:

I wouldn't be surprised if the book derived that number from the link you gave either.

clumsysmurf · 2016-12-29 · Original thread
A recent book that explores the loss of community when combat veterans come home, and how this may contribute to PTSD:

"Tribe: On Homecoming and Belonging"

Get dozens of book recommendations delivered straight to your inbox every Thursday.