The last full on book I've been reading is David Hume's An Enquiry Concerning Human Understanding. It's a great piece on epistemology or the way human beings gather and verify information in a rigorous and systemic way.

But if you count technical papers the last thing I read was the BAT whitepaper. If you're not familiar with BAT it's a token built off of the Brave browser which was designed to increase data and battery efficiency by blocking ads and trackers and rewarding users for their attention to advertisements with the BAT token. I can't get into too much detail but I think it has HUGE potential; it's built by industry experts that helped build Firefox; and it's at a pretty low price of about $0.30 which means there's potential for a huge ROI.