\begin{thebibliography}{1}

\bibitem{bartle}
Richard Bartle.
\newblock Hearts, {Clubs}, {Diamonds}, {Spades}: {Players Who} suit {MUDs}.
\newblock http://aigamedev.com/open/interviews/mario-ai/, 1996.
\newblock [Online; accessed 18-March-2012].

\end{thebibliography}