\begin{thebibliography}{1}

\bibitem{kn:peano}
Frederik Eriksen.
\newblock Et bevis i peano aritmetik, 2005.
\newblock Logiweb-dokument tilg\ae{}ngelig p\aa{} hjemmesiden:
  \url{http://www.diku.dk/~grue/logiweb/20050502/home/eriksen/peano-commutativ%
ity/GRD-2005-06-29-UTC-11-26-23-740136}.

\bibitem{kn:gold}
Derek Goldrei.
\newblock {\em Classic Set Theory --- For Guided Independent Study}.
\newblock Chapman \& Hall, 1996.

\bibitem{kn:base}
Klaus Grue.
\newblock A logiweb base page.
\newblock Logiweb-dokument tilg\ae{}ngelig p\aa{} hjemmesiden:
  \url{http://www.diku.dk/~grue/logiweb/20060417/home/grue/base/GRD-2006-06-06%
-UTC-07-18-19-012409}.

\bibitem{kn:check}
Klaus Grue.
\newblock The logiweb sequent calculus.
\newblock Logiweb-dokument tilg\ae{}ngelig p\aa{} hjemmesiden:
  \url{http://www.diku.dk/~grue/logiweb/20060417/home/grue/check/GRD-2006-06-0%
6-UTC-07-49-23-045248}. Dokumentet er fordelt p\aa{} tre .pdf-filer, hvis
  adresser (relativt til den ovenst\aa{}ende adresse) er:
  \href{http://www.diku.dk/~grue/logiweb/20060417/home/grue/check/GRD-2006-06-%
06-UTC-07-49-23-045248/body/tex/page.pdf}{body/tex/page.pdf},
  \href{http://www.diku.dk/~grue/logiweb/20060417/home/grue/check/GRD-2006-06-%
06-UTC-07-49-23-045248/body/tex/appendix.pdf}{body/tex/appendix.pdf} og
  \href{http://www.diku.dk/~grue/logiweb/20060417/home/grue/check/GRD-2006-06-%
06-UTC-07-49-23-045248/body/tex/chores.pdf}{body/tex/chores.pdf}. De to
  f\o{}rste filer er s\aa{} langt de vigtigste.

\bibitem{kn:hrba}
Karel Hrbacek and Thomas Jech.
\newblock {\em Introduction to Set Theory}.
\newblock Marcel Dekker, third edition, 1999.

\bibitem{kn:mendel}
Elliott Mendelson.
\newblock {\em Introduction to Mathematical Logic}.
\newblock Chapman \& Hall, fourth edition, 1997.

\end{thebibliography}