cite figure

doc/slides/slides.tex

@@ -42,7 +42,7 @@
   \begin{figure}
     \centering
     \includegraphics[width=5.0cm]{figs/math.eps}
-    \caption{``Five Aspects of Math Artefacts'' taken from~\cite{tetra}.}
+    \caption{``Five Aspects of Math Artifacts'' taken from~\cite{tetra}.}
   \end{figure}
 
   \begin{itemize}