I found several books for research I needed to do as either Kindle books (I don’t have a Kindle but have a Kindle reader on both my PC and my iPad) or as audio books through Audible. As we moved to Malaysia in the middle of my research and book, I wasn’t able to bring tons of materials along with me–nor are there libraries here with what I need.
I’ve listened to Audiobooks in the kitchen while cooking or clearing, etc, or in the bathtub–and like the ability to bookmark and comment on specific things to go back to.
I often carry my iPad and if I go out for a coffee or stop somewhere for lunch, I get it out and do a bit of quick thinking and reading. Again, I can bookmark things to go back to.
The Kindle books cost less than print volumes, I have an Audible subscription for those–and I’ll always have them without worrying about shipping them home someday.
While this doesn’t work for everything, for background books it’s been ideal for me. Some books I’ve listened to several times just to go over and over the details of the war, which were at first very confusing to me.