Citations never italicized

Question

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)?

Answer 1

You can wrap the citation in a \textup, like

\textup{\cite[Theorem 8.3]{Cha-Les-Zha11}}