Date not showing in citations natbib

Question

I'm using nat bib for beamer and my citations are all showing up with n.d., despite the citations having a date in the bib file.

\documentclass{beamer}
\usepackage{natbib}
\bibliographystyle{agsm}
\usepackage[german]{babel}

\begin{document}
  \begin{frame}
    \frametitle{Example citation}
    This is an example text with a citation from \citep{burzio1988ItalianSyntaxGovernmentBindingApproach} (← which is without date here and in the bibliography)
  \end{frame}

  \begin{frame}
    \frametitle{Bibliography}
    \bibliography{MyLibrary}
  \end{frame}
\end{document}

Here's the citation information in the bib file (which is in the same working folder):

  @article{burzio1988ItalianSyntaxGovernmentBindingApproach,
  title = {Italian {{Syntax}}: {{A Government-Binding Approach}}},
  shorttitle = {Italian {{Syntax}}},
  author = {Burzio, Luigi},
  date = {1988-03},
  journaltitle = {Language},
  shortjournal = {Language},
  volume = {64},
  number = {1},
  eprint = {414791},
  eprinttype = {jstor},
  pages = {130},
  issn = {00978507},
  doi = {10.2307/414791}
}

This happens with all citations styles on natbib. I don't know what's happening. I'll appreciate the help.

Answer 1

For bibtex, use the old year and month fields instead of date:

\documentclass{beamer}
\usepackage{natbib}
\bibliographystyle{agsm}
\usepackage[german]{babel}

\begin{filecontents*}[overwrite]{\jobname.bib}
  @article{burzio1988ItalianSyntaxGovernmentBindingApproach,
  title = {Italian {{Syntax}}: {{A Government-Binding Approach}}},
  shorttitle = {Italian {{Syntax}}},
  author = {Burzio, Luigi},
  year = 1988,
  month = 3,
  journaltitle = {Language},
  shortjournal = {Language},
  volume = {64},
  number = {1},
  eprint = {414791},
  eprinttype = {jstor},
  pages = {130},
  issn = {00978507},
  doi = {10.2307/414791}
}
\end{filecontents*}

\begin{document}
  \begin{frame}
    \frametitle{Example citation}
    This is an example text with a citation from \citep{burzio1988ItalianSyntaxGovernmentBindingApproach} (← which is without date here and in the bibliography)
  \end{frame}

  \begin{frame}
    \frametitle{Bibliography}
    \bibliography{\jobname}
  \end{frame}
\end{document}

If you prefer to use the date field, switch from bibtex to biblatex. Biblatex not only supports the superior date field, but is also much more flexible and easier to customise.