Not just semi-autos, but very old, uncommon pumps, twenty years ago, one could find , without trying too hard information on little know early shotguns, not just the Spencer pump.
Now such information seems to be gone, so, unless you know the name you are looking for, putting a search for -- little known early pump shotguns, gives you the Spencer and nothing else.
Searching for shotgun any way brings a lot of the Fortnight BS, and other online games nowadays rather than information on real shotguns.
The net used to be a good place to find what you once had to search for in books and magazines, well magazines are a joke now, and such books are out of print for decades, while at the same time the net is becoming a log of same crap, different pile Bovine Feces.