This might be yesterday's news to some of you but it's brand new to me. Millions of digitized titles in a searchable database (and a mobile app too). https://www.hathitrust.org/
What an extraordinary resource, familiar with which I was not. Thank you so much, Kizmet. It is, at least for the moment, my #2 bookmark, right after fivethirtyeight.com. --John