Presumably a fuller version will be given in author John Farrell's new book, for which this seems to be a promotion.
More interesting to me is this throwaway line, also presumably to be expanded in the book:
They contain other gems, like Haldeman’s notations of a promise, made by Nixon to Southern Republicans, that he would retreat on civil rights and “lay off pro-Negro crap” if elected president.
That's why voters were justified during the election of 2016 in believing that the policies of the Republican Party were antiblack. They have been consistently for the past 44 years, a disgraceful change from the previous policy of at least the liberal wing of the party. Yes, children, there used to be liberal Republicans, as there were conservative Democrats.