Change as suggested by Peter Funk <pf@artcom-gmbh.de>:
Create a hyperlink between the language reference and documentation for
the built in functions.
diff --git a/Doc/ref/ref5.tex b/Doc/ref/ref5.tex
index 406d259..db98fe4 100644
--- a/Doc/ref/ref5.tex
+++ b/Doc/ref/ref5.tex
@@ -453,8 +453,9 @@
\obindex{function}
\item[a built-in function or method:] The result is up to the
-interpreter; see the library reference manual for the descriptions of
-built-in functions and methods.
+interpreter; see the \citetitle[../lib/built-in-funcs.html]{Python
+Library Reference} for the descriptions of built-in functions and
+methods.
\indexii{function}{call}
\indexii{built-in function}{call}
\indexii{method}{call}