Book Reccomendation For Bugatti Royale

I don't believe that there's been a book written exclusively about the Royale cars. With only 6 built, there are interesting stories about ownership, but probably not enough for a full blown book. There are a couple of museums that may be able to give you further information, see below.

The Coupe Napoleon and the Limousine Park-Ward both reside in the ex-Schlumpf collection, the Musee National de l'Automobile de Mulhouse, in France. The Limousine Park-Ward was acquired by the Schlumpfs as part of a collection of cars bought from John Shakespeare (of the United States) in 1963. There was a much publicity about this collection being loaded on a train for the first part of their journey to France.

The Cabriolet Weinberger is in the Henry Ford (museum) in Michigan. It was rescued from a junk yard in New York in 1946.

The Coupe de ville Binder is owned by Volkswagen. It once resided in the Harrah Collection in Reno, and was sold to Major General William Lyon when Holiday Inn liquidated the majority of the collection in 1986.

The Kellner car is privately owned, whereabouts unknown.

The Berline de Voyage was made somewhat famous when owned by Tom Monaghan of pizza fame, who bought it from a then heavy-duty collector in Houston, Jerry Moore. This car is now owned by the Blackhawk Collection in Danville, California. As a side note, I rode in this car (about 100 feet) when it was shown by Monaghan at a White Post Celebrates, a 3 year event hosted by the late Billy Thompson in White Post, Virginia. I was told by the fellow handling the car that every time it went on display, a $10,000 insurance surcharge was paid due to value of vehicle, hearsay but interesting.