To me, you should rewrite your own version of the materials you have used to learn. I do that in Obsidian, a personal knowledge management tool. I copy/paste

To me, you should rewrite your own version of the materials you have used to learn. I do that in Obsidian, a personal knowledge management tool. I copy/paste contente from the web in interconnected notes, and once the contents are no longer in their original form, but transferred into my own read/write notes, I refactor and reorganise them. After a few refactors, some contents from different sources are now next to another in the same text. Or disappeared completely because another source has a « better » explanation. You can draw your own things, or add images from the web. I think this process is a little bit like writing your own Wikipedia article. The funny part is that when you come back to your notes later, you are astonished by the density of information connected together (just like Wikipedia).