Another book I have is: Pius IX by Roberto de Mattei - although I have to admit that I have not started reading it yet as I have a number of other books I want to read first:
* amazon.com/Pius-IX-Roberto-Mattei/dp/0852446055*
I also have an older book; The Life of Pope Pius IX - by John R G Hassard which was not as detailed but had other anecdotes not found in the newer books. You can probably pick up more of these older biographies online.
If someone asked me to lend them a book on Pius IX I would hand them the first one - just because I have read it all and remember commenting on how good it was. I think it is best to read a few books by different authors to get a more complete biography.
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