Add a link to the mxNumber package.
diff --git a/Doc/lib/libmpz.tex b/Doc/lib/libmpz.tex
index 1e586dc..e19ee56 100644
--- a/Doc/lib/libmpz.tex
+++ b/Doc/lib/libmpz.tex
@@ -103,4 +103,9 @@
This project is building new numeric types to allow
arbitrary-precision arithmetic in Python. Their first
efforts are also based on the GNU MP library.}
+
+ \seetitle[http://www.egenix.com/files/python/mxNumber.html]{mxNumber
+ --- Extended Numeric Types for Python}{Another wrapper
+ around the GNU MP library, including a port of that
+ library to Windows.}
\end{seealso}