it seems that in the latest release of the showlabels package the command `\showlabels{bibitem}` breaks the output of bibliographic tags containing accented symbols, see MWE attached, and the difference commenting out `\showlabels{bibitem}` makes. (From Michael Levitin, by email to Norman) MWE: \documentclass{article} \usepackage{showlabels} \showlabels{bibitem} \usepackage[colorlinks,allcolors=blue]{hyperref} \begin{document} We will use \cite{Pol54} \begin{thebibliography}{999999} \bibitem[P{\'o}lya]{Pol54} G. P\'{o}lya, \emph{Mathematics and plausible reasoning}, in two volumes, Princeton University Press, Princeton, N. J., 1954. \end{thebibliography} \end{document}