Section 22.2 External links
If you want to provide a link to a resource outside of your project, you will want the <url> tag. The code
<url href="https://pretextbook.org" visual="pretextbook.org">PreTeXt</url>
produces PreTeXt 1 . Note that the footnote is automatically created by the use of @visual.
Extensive details are provided in Section 4.27.
pretextbook.org