Add link to the gmpy project.
diff --git a/Doc/lib/libmpz.tex b/Doc/lib/libmpz.tex
index f0d2d6b..1e586dc 100644
--- a/Doc/lib/libmpz.tex
+++ b/Doc/lib/libmpz.tex
@@ -96,3 +96,11 @@
The mpz-number must have a value greater than or equal to zero,
otherwise \exception{ValueError} will be raised.
\end{methoddesc}
+
+
+\begin{seealso}
+ \seetitle[http://gmpy.sourceforge.net/]{General Multiprecision Python}{
+ 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.}
+\end{seealso}