As a technical founder I'd like to learn more about the practical side of sales, marketing, accounting, legal, recruiting, pricing and etc.

Most of the online business courses and startup books are very high level and don't cover anything useful.

Are there any must read business textbooks, online courses or forums that you recommend?

I'm mostly looking for practical advice on how to handle marketing efforts, which metrics to track, how to not mess up anything on the legal/accounting side and how to handle the sales process (contracts, pricing, pitching, etc).

The best things that I've found so far are the YC lectures, SaaStr and random blog posts.