A Tour of The Opéra Cellars And the Phantom Legend as Passed Down দ্বারা Opéra Employees 

Here's more Philip J. Riley wrote on the history of POTO.

link

I like how none of the reviews have anything to do with Riley's book. I don't trust his writing, he likes to make up stories when it comes to his books as he writes a lot of "what if" 'history' of Hollywood and most of it is sensationalized.