I was asked for some book recommendations by a reader. His requests on general self-discipline and habit-forming stuff were easy enough to give recommendations on, but he also asked for some good jumping off material to learn about "democracy and other forms of government" - my reply follows -
On government... hmm... I've read a lot on the topic, but no one work stands out to me as must-read stuff. Usually what I do is put a historical era into Wikipedia, do a "wiki walk" for a while, and then google the most interesting people and events for other insights.
You might consider Machiavelli's "The Prince," which was well-read and well-admired by most of the American founding fathers. I just read "Machiavelli, Violence, and History" which is a short essay -
Machiavelli is widely misunderstood because his most striking quotes - like, "Better to be feared than loved" - are taken out of context. The essay I just linked you to talks about violence in pursuit of the common good, things like that which can be a bit of a head-trip.