You can also type in "nuclear weapon launch safeguards", then follow down the list, read the articles, and pursue further leads.
I'm 71, and I've read all about this stuff beginning in the in the 50's and 60's. We did the "Duck and Cover" thing in our schools, in little towns that had absolutely zero military value, and would have never been targeted. Seems that almost everyone was enthralled by the prospect of being instantly vaporized, entertaining themselves by terrorizing themselves.