referencing labels from other files

Question

Sometimes I want to refer (using \ref) a \label from some other tex file. What is the right way to do it?

(It's, of course, possible to \include all files in one and then use \includeonly — but it breaks e.g. page and section numbering.)

Answer 1

https://texfaq.org/FAQ-extref

Referring to labels in other documents

When producing a set of inter-related documents, you’ll often want to refer to labels in another document of the set; but LaTeX, of its own accord, doesn’t permit this.

So the package xr was written: if you say

\usepackage{xr}
\externaldocument{volume1}

will load all the references from volume1 into your present document.

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