%%
%% The LaTeX Companion, 2ed (second printing August 2004)
%%
%% Example 3-3-22 on page 143.
%%
%% Copyright (C) 2004 Frank Mittelbach, Michel Goossens,
%%    Johannes Braams, David Carlisle, and Chris Rowley
%%
%% It may be distributed and/or modified under the conditions
%% of the LaTeX Project Public License, either version 1.3
%% of this license or (at your option) any later version.
%%
%% See http://www.latex-project.org/lppl.txt for details.
%%

\documentclass{ttctexa}
\pagestyle{empty}
\setcounter{page}{6}
\setlength\textwidth{135.0pt}

% FAKE: definition for \cite to fit book bibliography !!!
\renewcommand\cite[1]{[87]}
% FAKE: in real life this example should have a bibliography!!!

\StartShownPreambleCommands
\usepackage{amsthm}
\newtheoremstyle{citing}%  Name
  {3pt}{3pt}%              Space above and below
  {\itshape}%              Body font
  {\parindent}{\bfseries}% Heading indent and font
  {.}%                     Punctuation after heading
  { }%   Space after head (" " = normal interword space)
  {\thmnote{#3}}%          Typeset note only, if present
\theoremstyle{citing}   \newtheorem*{varthm}{}
\StopShownPreambleCommands
\begin{document}
\begin{varthm}[Theorem 3.16 in \cite{Knuth90}]
By focusing on small details, it is possible to
understand the deeper significance of a passage.
\end{varthm}
\end{document}
