I spent part of my day scouring the resources available at our library as well as commercial bookselling websites to see what other material might be out there. This kind of deep dive means that I'm reading book and article summaries, I'm reading footnotes, and I'm reviewing bibliographies. Everything I do is to sample what is out in the vast world of reading and information. I get to follow breadcrumbs to track down the next good thing.
Even if the subject is only in the periphery of my interest, I love building reading lists. I learn a ton of stuff and I know that I'm making a patron happy.