# Citations never italicized

I have some citations which appear inside a theorem like

\begin{thm}[The Strong Perfect Graph Theorem]\cite[Theorem 8.3]{Cha-Les-Zha11} A graph
$G$ is perfect if and only if neither $G$ nor $\bar{G}$ contains an induced odd cycle
of length 5 or more.
\end{thm}


where thm is defined by

\newtheorem{thm}{Theorem}


This citation appears in italics in the PDF. But, if I were to do the exact same citation outside of a theorem, it would not appear in italics. Is there a way to force it to always be plain (not italicized)?

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As far as I know, the environment thm is not standard in LaTeX. Did you use a package or did you define this environment in your preamble? – Vivi Dec 20 '12 at 22:55
@Vivi True, sorry. I added an explanation. – Graphth Dec 20 '12 at 23:00

You can wrap the citation in a \textup, like
\textup{\cite[Theorem 8.3]{Cha-Les-Zha11}}