link to wikibooks entry

$$

The example above was taken from the chapter _Typesetting Mathematical Formulae_,

in [The Not So Short Introduction to LaTeX](https://tobi.oetiker.ch/lshort/lshort.pdf),

which provides a good reference guide for those wishing to add equations

in [The Not So Short Introduction to LaTeX](https://tobi.oetiker.ch/lshort/lshort.pdf).

[The Mathematics chapter of the LaTeX WikiBook](https://en.wikibooks.org/wiki/LaTeX/Mathematics)

is a good reference guide for those wishing to add equations

and mathematical expressions to their lessons.

{% include links.md %}