Try the r/learnprogramming resource pages: free books, online stuff.

Can't actually name a good general article on pointers. They're the big sticking point for anyone trying to learn C for the first time, but they end up just being this sort of ubiquitous background knowledge everyone takes for granted pretty fast. I did stumble into Learn C the Hard Way, which does get around to pointers.

The C2 wiki is an old site for general programming knowledge. It's old, the navigation is weird, and the pages sometimes devolve into weird arguments where you have no idea who's saying what. But there's interesting opinionated content to find there, where sometimes the opinionators even have some idea what they're talking about. Here's one page on what they have to say about pointers.

Also I'm just going to link this article about soft skills involved in programming, because it's neat.