Cite two papers with same first author and year

I am using chicago.sty to reference papers. At one point, I have to reference two papers with the same first author and the same year. I don't want to use the cite option that shows all the authors. Instead I would like something like "Smith et al. (2009a)" and "Smith et al. (2009b)".

Is there a way I can do this (without changing to natbib)?

Here is an example:

\documentclass{report}
\usepackage{chicago}
\usepackage{filecontents}
\begin{document}

\begin{tabular}{llll}
shortcite     & \shortcite{Smith2012}
citeyear      & \citeyear{Smith2012}  \\
\end{tabular}

\begin{tabular}{llll}
shortcite     & \shortcite{Smith2012b}
citeyear      & \citeyear{Smith2012b}
\end{tabular}
\bibliographystyle{chicago}
\bibliography{references}
\end{document}

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Welcome to TeX.sx! I can't help but to suggest you consider moving to biblatex, which has chicago style (biblatex-chicago) –  henrique Nov 30 '12 at 15:51
Thank you @henrique, but I have tried that before, and could not get citeyear to work. I will try it again. –  Sara Nov 30 '12 at 15:55

Although you specifically asked for a bibtex solution for the chicago package, I couldn't resist to point you to biblatex, since Chicago Manual of Style biblatex style files are provided by the biblatex-chicago package.

To change the number of authors that trigger the "et al." string in biblatex, you have the options maxnames and minnames. Setting them to 1 takes care of your request (it is worth noting, however, that according to biblatex-chicago manual, this is not recommended by the Chicago Manual of Style). These options can be passed to biblatex-chicago package.

You mentioned in your comments not getting \citeyear to work in biblatex; this might be because \citeyear only prints the year field, without the extra label that is appended to disambiguate it. But this is achievable by the \citeyear* command.

N.B.: Please notice that biblatex-chicago (v. 0.9.9.a) requires biber for its author-year style, as stated in the manual (§2):

[Biber] is required for users who are either using the author-date style or processing a .bib file in Unicode.

That means you should replace the bibtex pass for a biber one. Compile this with [pdf]latexbiber[pdf]latex[pdf]latex

Here's a MWE:

\documentclass{article}
%\usepackage{chicago}
\usepackage[authordate,backend=biber,maxnames=1,minnames=1]{biblatex-chicago}
\usepackage{filecontents}
\begin{filecontents}{\jobname.bib}
@article{Smith2012,
author = {A. Smith and B. Schmidt},
title = {A title},
journal = {A Journal},
year = {2012},
}
@article{Smith2012b,
author = {A. Smith and B. Schmidt},
title = {Another title},
journal = {Another Journal},
year = {2012},
}
\end{filecontents}

\begin{document}

\verb!autocite! is the main citation command: it knows if it is in text or in notes, and switches between \verb!\footcite! and \verb!\parencite! accordingly. \autocite[1]{Smith2012}, \autocite[1]{Smith2012b}

\verb!\footcite! is for citations on footnotes\footcite[1]{Smith2012}, \footcite[1]{Smith2012b}

\verb!\parencite! is for citations in parentheses \parencite[1]{Smith2012}, \parencite[1]{Smith2012b}

\verb!\textcite! is for inline citations, like \textcite[1]{Smith2012}, \textcite[1]{Smith2012b}

\verb!\citeyear! cites only the \verb!year! field, not \verb!year+label!: \citeyear[1]{Smith2012b}. To cite the whole label, you should try the starred variant \verb!\citeyear*!: \citeyear*[1]{Smith2012}, \citeyear*{Smith2012b}

You can also have multiple citations with some of these commands: \autocites{Smith2012}{Smith2012b}

%\bibliographystyle{chicago}
%\bibliography{\jobname}
\printbibliography
\end{document}


And the output:

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Thank you, but I do not get the same output as you with your code. I am getting some errors when executing bibtex: found no \citations commands, found no \bibdata command, found no \bibstyle command. This happens even if I move the bibliography to another file. I had this error before, and that is why I changed to chicago.sty –  Sara Nov 30 '12 at 16:45
Please, ignore the former comment, I've checked biblatex-chicago manual again, and it requires biber. Simply switch to biber in the bibtex pass. –  henrique Nov 30 '12 at 17:00
I will try that. I am using Texniccenter, so first I will have to check how to do it. I will get back to you. –  Sara Nov 30 '12 at 17:06
Ok, I updated the answer to mention that. For running biber form TeXnicCenter, check this question (but, instead of bibtex, search for the path to biber executable) –  henrique Nov 30 '12 at 17:10
It worked! I had to update biber for it to work though....Thanks!! –  Sara Nov 30 '12 at 18:41