- 数学：Free Math Resources - Textbooks, Lectures Notes, Videos and Online Courses | Real Not Complex
- https://app.diagrams.net/ 画图
- https://docs.python.org/ Python文档
- https://github.com/
- https://brilliant.org/ 学习
- https://www.csdn.net/ 中文技术
- https://wumbo.net/ (Wumbo is a math reference site for students, teachers, and enthusiasts.)
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