The declassified FBI files of Archbishop Fulton Sheen and Cardinal Spellman is worth reading about this
Fulton Sheen files http://foia.fbi.gov/foiaindex/sheen_f.htm
Francis Cardinal Spellman Files http://foia.fbi.gov/foiaindex/spellman.htm
This is interesting, because I’ve heard so much about the influence of communism on those Catholics who wrongly interpreted Vatican II. It remains a problem today.