> For the complete documentation index, see [llms.txt](https://ninjapay.gitbook.io/ninjapay-api-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ninjapay.gitbook.io/ninjapay-api-docs/other/helpful-references.md).

# Helpful references

[Bitcoin's Lightning Network, Simply Explained!](https://www.youtube.com/watch?v=rrr_zPmEiME)

[Lightning Network](https://lightning.network/)

[Just Enough Research by Erika Hall](https://abookapart.com/products/just-enough-research)

[WebUPI Guide (v1.0)](https://www.notion.so/WebUPI-Guide-v1-0-5cc252edc8444fc39039be34efb23647)

Also watch Lightning network basics to understand how the layer2 works 👇

{% embed url="<https://www.youtube.com/watch?v=SXT9iq__V8c&t=1s>" %}