# fix sorting for references with natbib for A&A

I'm currently preparing an article for Astronomy & Astrophysics, where the references have to be ordered as follows:

1. One author: chronologically
2. Author, one co-author: alphabetically by co-author, then chronologically
3. Author, two or more co-authors: chronologically.

But when using natbib with the provided .bst file the 3rd condition is not respected. Here's my MWE:

\documentclass{article}
\usepackage{natbib}
\bibpunct{(}{)}{;}{a}{}{,} %% natbib format for A&A and ApJ
\usepackage{filecontents}
\begin{filecontents}{sandbox.bib}
@Article{paper2,
author  = {{Alpha}, A. and {Beta}, B. and {Charlie}, C. and {Delta}, D. and {Echo}, E. and {Foxtrot}, F.},
title   = {Title. II. Subtitle},
journal = {ApJ},
year    = {2001},
volume  = {1},
pages   = {1-10},
}

@Article{paper3,
author        = {{Alpha}, A. and {Beta}, B. and {Charlie}, C. and {Delta}, D.},
title         = {Title. III. Subtitle},
journal       = {ApJ},
year          = {2001},
volume        = {1},
pages         = {11-20},
}
\end{filecontents}
\begin{document}

paper 2: \cite{paper2}

paper 3: \cite{paper3}

\bibliographystyle{aa}
\bibliography{sandbox}
\end{document}


Can I put a non-printed character somewhere in the bib file to fix that sort?

How would I have to change the author.sort function in the bst file to fix it permanently?

• So short version of your question: which changes do you want? – user36296 Nov 6 '17 at 15:29
• those changes necessary to get the references ordered according to the list at the beginning of my question – Markus Schmassmann Nov 6 '17 at 16:39