语法总结
https://blog.csdn.net/ajacker/article/details/80301378
https://blog.csdn.net/jyfu2_12/article/details/79207643
https://qianwenma.cn/2018/05/17/mathjax-yu-fa-can-kao/
小技巧
markdown如何打出双下标 https://blog.csdn.net/u013698770/article/details/55210693>
CDN
国内 mathjax CDN https://www.bootcdn.cn/mathjax/
国外 mathjax CDN https://github.com/mathjax/MathJax-src
<scriptid="MathJax-script" asyncsrc="https://cdn.jsdelivr.net/npm/mathjax@3/es5/tex-mml-chtml.js"></script>