writer/designer Kim Eastland's "Realms of Magic" supplement for the 1980s Marvel Superheroes Roleplaying game is an underrated resource for categorizing the different types of magic sources (personal energy, universal energy, dimensional energy, etc.), limits of usage , and items/paraphernalia, and how they apply to different sorts of users. https://www.amazon.com/Realms-Magic-.../dp/0880382783
(there are, of course, "unofficial" copies floating out there on the interwebs)