Owen’s list is pretty comprehensive ( as we would expect). My only addition(s) would be the Stephen James O’Meara series from Cambridge. “The Secret Deep” and “Hidden Treasures“ have expansive entries on PNs. The first volume on the Messier objects is not really needed and the second ( the C……… objects) has a few. Some may be irritated by the rather idiosyncratic nicknames on offer but the meat of the info is good.