TeX commands table (cheatsheet) https://calculla.com/mathjax_cheat_sheet
TeX Commands available in MathJax https://www.onemathematicalcat.org/MathJaxDocumentation/TeXSyntax.htm
MathJax basic tutorial and quick reference https://math.meta.stackexchange.com/questions/5020/mathjax-basic-tutorial-and-quick-reference (MathJax basic tutorial and quick reference https://math.meta.stackexchange.com/questions/5020/mathjax-basic-tutorial-and-qu%E2%80%8C%E2%80%8Bick-reference)
MathJax basic tutorial and quick reference https://www.physicsoverflow.org/15329/mathjax-basic-tutorial-and-quick-reference
MathJax https://www.mathjax.org/
MathJax source https://github.com/mathjax/mathjax
Grav MathJax plugin https://github.com/Sommerregen/grav-plugin-mathjax
See also TeX/LaTeX