I have seen it mentioned in passing that he was a Mason , exactly what books have any real info about it , I can't recall off-hand. Maybe I will dig a little to find something , but whatever I have in any of my books, is probably not much compared to what you might be able to find yourself.
I have shied away from the Masonic/illuminati conspiracy stuff about the motivations of some world leaders in 1900's. There seems to be enough conspiracy stink about Roosevelt, Churchill, et al., without YET looking at this.
Besides the minute you start asking about such things , remember this sort of stuff has all been categorized as Nazi propaganda ( i.e. Masonic/Judeo/Bolshevich conspiracy theory)