There’s probably no one who knows more about startups than Paul Graham. Having helped thousands of startups through Y Combinator, the startup accelerator he co-founded, there’s a thing or two to learn from his essays. And Graham’s wisdom isn’t limited to startups either; his essays, read by millions, touch on education, intelligence, writing, society, the human mind, and much more.

Paul Graham 101 by Jaakko

An alternative on the subject of startups is probably Jessica Livingston's Founders at Work. I don't have a third source so it doesn't qualify for The Best Textbooks on Every Subject.