The Republic - Plato - why societies form the way they do
Either/Or - Kierkegaard - as a father of Existentialism his views on society helped put things in perspective for me
It's All About Time - John Furey - surprised I don't see this mentioned more - how people organise their thinking based on a time-based motivational model https://www.amazon.com/Its-All-About-Time-Companies
On the topic of mental models, others have mentioned Feynman - but here's a discussion on why he was such an unusually effective scientist partly because of his use of less common mental models http://jamesclear.com/feynman-mental-models
Either/Or - Kierkegaard - as a father of Existentialism his views on society helped put things in perspective for me
It's All About Time - John Furey - surprised I don't see this mentioned more - how people organise their thinking based on a time-based motivational model https://www.amazon.com/Its-All-About-Time-Companies