Here I provides some useful links. I will not try to organise them because it is impossible. Always feel free to contact me about these links, if you find some inaccessible or you have new links. But there will only be text-focused links.
- Say no to compulsive hoarding. You don't need to collect everything before studying.
- Don't make use of information asymmetry. Just don't.
- I claim no credit or originality of these links
- The symmetric functions catalogue
- Real Not Complex - Discover Incredible FREE Resources to Study Mathematics
- MIT Open Courseware
- The Stacks project - an open source textbook and reference work on algebraic geometry
- Note and resources provided by Keller VandeBogert
- SageMath - Open-Source Mathematical Software System
- What's new - Terrence Tao's blog
- Gowers's Weblog - Mathematics related discussions
- AMS BLOGS - Graduate Student Blog
- How to study maths really quick (YouTube)
- How to study maths really quick (Bilibili)