When I check the "help" of Super User, I found this:
it is not about …
asking for a product, service or learning material recommendation
I understand no one like ads. However, it says "learning material recommendation" rather than "for-profit learning material recommendation". So I'm wondering where can I ask for related information - this means the wanted info (mostly not the knowledge itself, but the links to documents/sites/blogs/specifications/...) is fairly broad and is generally not allowed in most of the SE sites.
Where can I find X related document? is simply not an specific X question and is often closed.
The alternative - to separate this into multiple (perhaps hundreds of) specialized questions - is kind of like "polluting the site".
As for some "cold" topics, Wikipedia isn't very useful (hard to find the right entries) and web search engines just repeat the same popular contents (of little relevance) for pages (even with extensions to block those copycats).