# Citing in Beamer: Year depiction problem in the reference slide

I am preparing a presentation with beamer package with multiple citations. Therefore I have decided to use the following packages:

\usepackage[style=apa, backend = biber]{biblatex}
\DeclareLanguageMapping{american}{american-UoN}


Within the cited slide I have no problems, however in the references slide, which I produces via:

\begin{frame}[t,allowframebreaks]
\frametitle{References}
\printbibliography
\end{frame}


The year is not shown. I have compiled the bib and tex files multiple times. Unfortunately no luck. The citation in the slide stays as:

And the reference slide as :

I would appreciate any help. Thank you in advance

Note: bib entry for this reference is like the following:

@phdthesis{beall2003role,
title={The role of reverse auctions in strategic sourcing},
author={Beall, Stewart},
year={2003},
school={Arizona State University}
}


In the definition frame I call it with:

lower priced bids during a scheduled time period.'' \cite{beall2003role}

And the reference frame looks like the following:

\begin{frame}[t, allowframebreaks]{References}
\printbibliography
\end{frame}

• Could you show the bib file for this reference and how you call it in the beamer frame? – pluton Jun 11 '15 at 10:09
• Welcome to TeX.SX! Please edit the details of the reference in to your question. – Andrew Swann Jun 11 '15 at 10:15
• What happens if you remove the apa style and use the default style instead? – pluton Jun 11 '15 at 10:21
• Thank you @pluton apparently APA was the problem. As soon as I removed it the problem is solved. – Aysegul Engin Jun 11 '15 at 10:29
• What exactly is american-UoN.lbx as in \DeclareLanguageMapping{american}{american-UoN}. The biblatex-apa styles needs some macros defined in <language>-apa.lbx, so one always has to load \DeclareLanguageMapping{american}{american-apa}. So your construction will only work if american-UoN.lbx provides the macros necessary... – moewe Jun 11 '15 at 15:33

When using biblatex-apa one needs to include a call for biblatex-apa's language files. Amongst others, these .lbx files contain biblatex-apa's date macros that are used to format the dates in the bibliography.
After loading biblatex, a line aking the lines of \DeclareLanguageMapping{<language>}{<language>-apa} should be added; in our example that would be
\DeclareLanguageMapping{american}{american-apa}