This is one of the core questions of PKM and there are established methods to solve it. Since no-one’s mentioned it yet, I’ll mention Zettelkasten. The Zettelkasten method is one way to store your thoughts on literature and link it so that the value of your notes compounds over time.
If you use this method - you won’t quote the author verbatim, you’ll write the gist of what they were saying in your ‘literature notes’. Keeping the source material in your reference manager.
The abbreviated notes you are taking are better than re-writing verbatim because the aim with Zettelkasten is reinterpreting the gist in your own words. The effort to reinterpret and explicitly write out what they’re saying are central to understanding and remembering it. This is the trap of copy-paste. You don’t really engage with the text this way and therefore don’t retain it.
Learning is work. You can make the work more effective, but it cannot be skipped.
The easiest introduction is watching a video. The best introduction is reading the first section of a book.
Zettelkasten is powerful, but what most videos don’t tell you is:
Zettelkasten requires changing your entire workflow to realise its benefits.
It’s not just a tool. It’s your whole workflow and environment that need to be aligned.
This is the crucial piece many people miss. Trying to add it on top of what you do already won’t work well. It’s an enormous commitment.
Tools are secondary to the mindset, workflow and process.
Obsidian lends itself well to zettelkasten. But there are plenty of other tools out there which will suffice - even pen and paper. Most of the work - reading, engaging, reinterpreting, thinking and linking must be done by you. Some people still prefer pen and paper over software because it forces them to do the work.
A much better introduction is part 1 (the first 4 chapters) of Sonke Ahren’s excellent book, How to take smart notes. It’s also an excellent guide if you commit to building your own Zettelkasten.
Many explanations have focused just on the Zettelkasten. Not on its skillful use as part of the workflow. Ahren’s book describes how it worked and why it worked.
So we can emulate and tweak ourselves so we can use for learning, writing and research.
A search of this forum or online for zettelkasten will yield plenty of results with different folks discussing and showing their workflow and implementations.