I'll have to order it:

One of my quirks," he writes, "has been to keep track of the retirement of senior generals and admirals; those who did not get to the top invariably had a story to tell in explaining why."

He even watches for obituaries, which often let slip surprising information about the pasts of, say, deceased CIA operatives. And he will call wives or relatives and search for information that way.

Hersh, in other words, works from the edges inward, developing a grapevine of faceless sources that in turn generate rumors and stories of things he isn't supposed to know...

Another great review at the Intercept.