Mushroom libraries
There are a multitude of these, so I won't go into detail about every one of them.
There is one called The yellow library, which is easy to access for beginners, look up, to your right, then lean back a bit until you can see a valley with mountains around it. Project there and follow the paved road to the city center. The library is on the hill right up on ahead, then to the left, follow the road. To gain access you need to perform an entry procedure where your abilities are measured. If you don't qualify, they will tell you. Depending on your own pre-existing skill level, you will gain access to one of 3 existing sections. The librarian will explain the details.
The mushroom-Hebrew library
This is what you should aim for, but it's difficult to access. The location is up, somewhat to your left, look along the thick stone wall which appears. Project onto the platform and knock on the door. It may help to yell and make some noise as well. To enter here you need to match the racial DNA of the people living there, or you'll die from poison spores. This can be solved in different ways, either by sending a robot servitor inside which won't be harmed (but then you won't get library access because it's a robot) or by interacting with the population to somehow get this DNA. If you talk to them, you can find a solution.
This library has pay courses in "original Hebrew" which is used by this race of very poisonous fungus based humans. If you learn it, you can read pretty much any astral books later, because many languages are influenced by "mushroom hebrew".
It's a difficult place to visit and use, but well worth it. I still haven't seen all books after 6 months, I don't know how deep this library is.