\begin{thebibliography}{PWW88}

\bibitem[BKPS02]{BKPS}
Paul Beame, Richard~M. Karp, Toniann Pitassi, and Michael~E. Saks.
\newblock The efficiency of resolution and davis--putnam procedures.
\newblock {\em {SIAM} J. Comput.}, 31(4):1048--1075, 2002.

\bibitem[BP97]{BussP}
Samuel~R. Buss and Toniann Pitassi.
\newblock Resolution and the weak pigeonhole principle.
\newblock In Mogens Nielsen and Wolfgang Thomas, editors, {\em Computer Science
  Logic, 11th International Workshop, {CSL} '97, Annual Conference of the
  EACSL, Aarhus, Denmark, August 23-29, 1997, Selected Papers}, volume 1414 of
  {\em Lecture Notes in Computer Science}, pages 149--156. Springer, 1997.

\bibitem[CS88]{CS88}
Vasek Chv{\'{a}}tal and Endre Szemer{\'{e}}di.
\newblock Many hard examples for resolution.
\newblock {\em J. {ACM}}, 35(4):759--768, 1988.

\bibitem[Hak85]{Haken85}
Armin Haken.
\newblock The intractability of resolution.
\newblock {\em Theor. Comput. Sci.}, 39:297--308, 1985.

\bibitem[MPW02]{MPW}
Alexis Maciel, Toniann Pitassi, and Alan~R. Woods.
\newblock A new proof of the weak pigeonhole principle.
\newblock {\em J. Comput. Syst. Sci.}, 64(4):843--872, 2002.

\bibitem[PWW88]{PWW}
Jeff~B. Paris, A.~J. Wilkie, and Alan~R. Woods.
\newblock Provability of the pigeonhole principle and the existence of
  infinitely many primes.
\newblock {\em J. Symb. Log.}, 53(4):1235--1244, 1988.

\bibitem[Raz04]{raz-wphp}
Ran Raz.
\newblock Resolution lower bounds for the weak pigeonhole principle.
\newblock {\em J. {ACM}}, 51(2):115--138, 2004.

\bibitem[Urq87]{Urquhart87}
Alasdair Urquhart.
\newblock Hard examples for resolution.
\newblock {\em J. {ACM}}, 34(1):209--219, 1987.

\end{thebibliography}