Another crucial book in this regard is "His Master's Voice in America" By Frederick O Barnum III. Unfortunately, it was privately published by GE (which at the time owned RCA/Victor) and only a few hundred were ever printed, so you'll be lucky to find one. But in the US, Inter-Library Loan might find it. Elsewhere, I doubt if you'll have a chance of finding one!

I work in Camden, NJ, across from the old Victor plant, and L3 (what's left of Victor that has not spun off into GE, Lockheed Martin, Martin Marietta, etc) is a near neighbor. They still have a display in the L3 lobby of some of the early His Master's Voice paintings. There are also stained glass windows that shine over Camden with the Nipper image in them!