By Edward Jay Epstein. The first in what became Epstein's Assassination Chronicles trilogy, with an intro by Richard H. Rovere and blurbed by Dick Goodwin. Epstein was on the leading edge of published conspiracy thinking around the murder of JFK; the book came out in 1966.
So did this trim little paperback, which is very tidy and nice for a book this age: the spine leans a bit, but it's uncracked, and the pages are tight and clean, only mild toning. A fantastic reading copy.