Added some cross-references to the end.
diff --git a/Doc/lib/libshelve.tex b/Doc/lib/libshelve.tex
index 4b7f773..7a463cd 100644
--- a/Doc/lib/libshelve.tex
+++ b/Doc/lib/libshelve.tex
@@ -62,3 +62,9 @@
 requires knowledge about the database implementation used.
 
 \end{itemize}
+
+
+\begin{seealso}
+  \seemodule{pickle}{Object serialization used by \module{shelve}.}
+  \seemodule{cPickle}{High-performance version of \module{pickle}.}
+\end{seealso}