Where can I find Air Traffic Control information material suitable for beginners and students?
Another good reference would be the training materials for VATUSA. This is part of an online system called VATSIM where people both fly and provide ATC virtually.

Although some of it does not apply to real operations (and of course none of it should be actual operations), it still covers real procedures based on the actual rules.

The basic guides do a good job of providing an introduction to the basic concepts, but the more advanced stuff is less helpful.

Other regions have their own VATSIM organizations, if you prefer a region other than the US.

In addition to the materials available, participation is also great for learning. Through VATSIM you can get training on the materials and then get hands-on experience working with (virtual) traffic.