Ask HN: Please share advanced resources to level up

I would like to level up and learn some topics deeper (e.g. distributed systems, networking, data and storage). But, a lot of time I struggle to find structured resources to follow to go deeper in the topic.

Target audience of the most tutorials/guides (with a very good structure) are mostly oriented towards beginners, I need something similar but for advanced topics. Otherwise, I am jumping from one paper to another, with no clear structure, sometimes it's good, but a lot of times waste of time if paper doesn't bring something interesting.

Can you please share such resources? Could be about any topic.