+
+% The references can be tiny.
+\setbeamerfont{bibliography item}{size=\footnotesize}
+\setbeamerfont{bibliography entry author}{size=\footnotesize}
+\setbeamerfont{bibliography entry title}{size=\footnotesize}
+\setbeamerfont{bibliography entry location}{size=\footnotesize}
+\setbeamerfont{bibliography entry note}{size=\footnotesize}