\input eplain

\let\primitiveend = \end
\def\bye{\vfill\eject\primitiveend}

\def\begin#1#2{%
  \message{widest label is #2}
}
\def\end#1{}

Two citations to Knuthian works: \cite{surreal,concrete-math}.

\beginsection{References.}\par   % Title for the bibliography.

\bibliography{knuth}   % Use knuth.bib to resolve the labels.
\bibliographystyle{plain}   % Number the references.

\bye   % End of the document.
