Use a named reference to another chapter instead of hard coding the
chapter number. This also makes the reference a hyperlink in the HTML
version.
diff --git a/Doc/ref/ref5.tex b/Doc/ref/ref5.tex
index 37d1f2d..c736b0e 100644
--- a/Doc/ref/ref5.tex
+++ b/Doc/ref/ref5.tex
@@ -23,8 +23,8 @@
When a description of an arithmetic operator below uses the phrase
``the numeric arguments are converted to a common type,'' the
arguments are coerced using the coercion rules listed at the end of
-chapter 3. If both arguments are standard numeric types, the
-following coercions are applied:
+chapter \ref{datamodel}. If both arguments are standard numeric
+types, the following coercions are applied:
\begin{itemize}
\item If either argument is a complex number, the other is converted