It's in the Stanford libraries, or at least was when I read it years ago.
Also useful is "Men and Volts", an official history of General Electric.
From an investment perspective, it's worth reading the early history of the electrical industry, because it's very much like the history of the computer industry. Just a century earlier. You get to see something go from cutting edge technology with high margins to dull and boring with low margins, over half a century. You get to see the transition from thousands of little companies to a few big ones.
As you keep going into the radio era, you see the transition from paid services to ad-supported ones.
It will all look very familiar.