# “Extra }, or forgotten \endgroup” error with natbib package and plos2009 bibliography style

I'm preparing a manuscript for PLoS one Computer and information sciences Journal, which requires me to use their own special bibliography style (plos2009.bst[1])

This style is generating the following error with the natbib package (which I need for getting author citations like "Alwan et. al. 2009 [1]")

(./test.bbl
! Extra }, or forgotten \endgroup.
\par ...m \@noitemerr {\@@par }\fi \else {\@@par }
\fi
l.22

?
)


This is an example to test:

\documentclass[10pt]{article}
\usepackage[square,numbers,sort]{natbib} % to include \citeauthor styles
\bibliographystyle{plos2009}
\begin{document}
\section*{Introduction}
Testing a normal citation: \cite{Alwan2006}
Testing an author citation: \citet{Alwan2006}
\bibliography{test}
\end{document}


With this content on test.bib:

@inproceedings{Alwan2006,
Author = {Alwan, Majd and Rajendran, PJ and Kell, S and Mack, D. and Dalal, S. and Wolfe, M. and Felder, R.},
Booktitle = {ICTTA'06},
Doi = {10.1109/ICTTA.2006.1684511},
Isbn = {0-7803-9521-2},
Publisher = {IEEE},
Title = {{A Smart and Passive Floor-Vibration Based Fall Detector for Elderly}},
Year = {2006}
}


Edit (from comment by OP):

This is what I actually am expecting "Alwan et. al. [1]" or "Alwan et. al. 2009 [1]". I need both author-style and numeric-style citations.

-
I don't get any such error message. However, the plos2009.bst is not a natbib bibliography style (unlike e.g. plainnat), so you will not have access to the author name via \citet. –  Andrew Swann Jan 29 '14 at 11:28
@Mico I meant natbib. The bibliographystyle has to instruct bibtex to write information in the specific natbib format to the .bbl file so that natbib can pick up the author data. –  Andrew Swann Jan 29 '14 at 11:32
@cdparra -- you're giving conflicting information here. on the one hand, in a comment, you say you "want to use numeric-style citations", but in your question, you say you need natbib "for getting author citations like "Alwan et. al. 2009 1" ". which is it, or do you mean the references are to be numbered, and "Alwan et al. 2009 1" is how the beginning of the reference is to look in the listing, as opposed to the citation in the text? (by the way, no period after "et" in "et al.".) –  barbara beeton Jan 29 '14 at 13:49
@barbara: My mistake. This is what I actually am expecting "Alwan et. al. [1]" or "Alwan et. al. 2009 [1]". I need both author-style and numeric-style citations. –  cdparra Jan 29 '14 at 15:51
@cdparra -- i've edited your comment into the question; i hope the edit will have the effect of attracting more attention. however, i don't know of any bib-style or package (or combination) that simultaneously provides both the numbered and author-year styles of citations. perhaps someone else might. –  barbara beeton Jan 29 '14 at 21:18