There are many methods. That is the one I am familiar with. The best thing you can do is read a bunch of books on the subject until you get a feel for which ideas are the authors' or paradigm's bias and which ideas are essential to the practice and common between paradigms.
The Lesser Key of Solomon is rooted in the Abrahamic worldview. If that isn't your cup of tea, Wiccan texts will likely give you a very different approach to summoning spirits. Thelemic texts will give you yet another angle which is more similar to the Abrahamic angle than the Wiccan angle. The magical circle of protection, however, is common between many systems.
Read enough books from different paradigms and you will begin to grasp the underlying mechanism common to all of them.
If you want to summon "demons" in particular, then "goetia" is the keyword you should use in your search.