Anthony Rhodes (1916–2004)

Accurate unbiased history of the kind you don't find written today. Shows the Vatican's "realism" when it came to the changing political landscape of the 20th Century. Not always pretty and never as bad it may have seemed, it puts both Liberals and Traditionalists to the lie with facts.

I referred to this for research from time to time thus it was handy to have because it does detail Vatican relations in regards to 19th Century liberal democracies.