There have been several books out with info from the Soviet Archives. Don't remember which book had this. Might have been "The Sword and the Shield: The Mitrokhin Archive and the Secret History of the KGB" by Christopher Andrew and Vasill Mitrokhin.
Some KGB archives are on line here:
http://psi.ece.jhu.edu/~kaplan/IRUSS/BUK/GBARC/buk.html
They are in a mix of English and Russian with downloads. The books are easier to read.
If you check the Mitrokhin book at amazon.com, they will show five or six similiar volumes. One of them should mention Hoover in the review.