What are /r/collegecompare's favorite Products & Services?

From 3.5 billion Reddit comments

the best book I read on the history of the end of 19th and beginning of 20th centuries:

https://www.amazon.com/dp/B00INIXPYE/ref=dp-kindle-redirect?_encoding=UTF8&btkr=1

Prof Kotkin is a professor at Princeton.

Definitely Princeton (I'd recommend Yale as well since Timothy Snyder is there, but Kotkin is my hero)