+@bibdfn{Christopher}
+W.@: A.@: Christopher, S.@: J.@: Procter, T.@: E.@: Anderson,
+@cite{The Nachos instructional operating system}.
+Proceedings of the @acronym{USENIX} Winter 1993 Conference.
+@uref{http://portal.acm.org/citation.cfm?id=1267307}.
+