% File to test the various customizations btxmac.tex allows.
% 
\input eplain

% Have citations come out as superscripts, as in footnotes.
% 
% Unfortunately, plain TeX doesn't define the \scriptfont for the \tt
% family. Since we use \tt to print unresolved bib-references, we define
% it ourselves, so we can use superscripts.
\font\eighttt = cmtt8
\scriptfont\ttfam = \eighttt
\def\printcitestart{$^\bgroup}
\def\printbetweencitations{,\space}
\def\printcitefinish{\egroup$}
\def\printcitenote#1{\hbox{\sevenrm\space (#1)}}

% Do angle brackets instead of brackets. (We don't redefine \biblabelprint.)
% 
\def\biblabelcontents#1{\bblrm $\langle$#1$\rangle$}

% Use sans serif instead of roman, and slanted instead of italic.
% 
\font\bblrm = cmss10
\font\bblem = cmsl10

% Put a rule before the bibliography.
% 
\def\bblhook{\medskip\hrule\smallskip}

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

This one with a note: \cite[another one]{surreal}.

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