I've started dabbling a bit in magick (I spell it with the 'k' to distinguish the actual craft in my mind from "stage"/"illusion" magic), and the thing I learned most quickly is that
"mundane
" rolleyes topics, like math, chemistry, and physics, are actually far better study points for me than books all about spells. Perhaps it's because I pretty much regard such fields as basically the closest thing to magick as depicted in Western High Fantasy (D&D describes it as involving lots of complicated calculations and counter-intuitive equations). Maybe also because it helps provide a ... "lifeline" of sorts, to keep me safely tethered to "this" world so I don't get completely lost and go insane while exploring the "other" world (as is FREQUENTLY stressed in the Old Stories about such journeys as being basically mandatory for safe travels there).
So, based on my little dabblings, I'd say you'd want to go a LOT further than just "different authors". You'd also want to study a variety of topics that could be involved, particularly things that are counter to your own comfort zone of skills and knowledge yet carry some intriguing air of "mystical". In any kind of research, sticking with a single source is NEVER a good idea, because that single source will always have biases. (Despite what certain individuals and media outlets often claim about themselves, it's 100% impossible to be unbiased and objective). You do, too, and always will, but unless you're part of a group that places a lot of emphasis on conformity, you want those biases to be mostly your own, and the best way to do that is to be informed by multiple sources.
In Olden-Days, these crafts took YEARS of study, and in unbroken indigenous traditions, that's still the case. Sure, a lot of the knowledge studied back then also involved things that are covered nowadays in primary education, but we also have a LOT more distractions these days just from media and social obligations. Patience is the key, and it's an ongoing process.