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# References

## The reference list

The reference list should contain all the references cited in the text, ordered alphabetically by surname (with initials following). If there are several references to the same first author, they should be entered according to the following scheme:

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

The first three author's names are given, followed by "et al.", for papers written by a group of more than five authors.

Papers in preparation (not yet submitted to a journal) are not to be displayed in the reference list and are to be listed as "in prep." in the main text, without any date.
Private communications are not listed either and may be acknowledged as "YYYY, priv. comm." in the main text.
For papers submitted to a journal that are not yet published, please give the year of submission/acceptation, the name of the journal, and its status: submitted (not yet accepted), or in press. Citations should only mention the year given in the reference.

The A&A format for references is as follows:

• Bohr, N., Einstein, A., & Fermi, E. 1992, MNRAS, 301, 257 (BEF)
• Curie, M., & Curie, P. 1991, A&A, 248, 612
• de Gaulle, C. 1996, Solar Phys. (Oxford Univ. Press, Oxford)
• Heisenberg, W., & West, C. N. 1993, Australian J. Phys., 537, 36 (Paper III)
• Laurel, S., & Hardy, O. 1994, Active Galactic Nuclei, in The Evolution and Distribution of Galaxies, ed. W. Churchill, F. D. Roosevelt, & J. Stalin (Wiley, New York), 210

To set the reference list in the proper A&A format, we encourage you to use BibTeX and the natbib package instead of the standard thebibliography environment.

## How to use BibTeX for A&A

For extensive description of the general use of BibTeX, please see for example The LaTeX Companion p.757 (Franck Mittelbach and Michel Goosens, second edition).

To use BibTeX, you must:

1. Create a database (.bib) file that describes the articles or books you want to reference. The NASA Astrophysics Data System (ADS) provides automatic tools for retrieving a .bib file including entries for a selection of articles. An example of a typical .bib file is also provided in the A&A LaTeX macro package.
2. Specify the style and location of the bibliography in your TEX document. The A&A package includes a style file aa.bst that will format your reference list in the proper A&A format. Before running BibTeX you must ensure that the requested files (i.e. bib, bst and sty files) are in the same directory as your TEX files.
3. Run BibTeX then run LaTeX. Remember you must run LaTeX twice to update the citations.

In the TEX file, the references list is enclosed as follows:

 \documentclass{aa} ... \usepackage{natbib} \bibpunct{(}{)}{;}{a}{}{,} % to follow the A&A style ... % for the bibliography, at the end \bibliographystyle{aa} % style aa.bst \bibliography{Yourfile} % your references Yourfile.bib \end{document} 

## Citations in the text

References are normally cited in the text by placing the name(s) and the year in parentheses, without any comma between them. If there are two authors for one citation, both names should be given, separated by an ampersand (&). If there are more than two authors, only the first name should be given, followed by "et al.". Commas should be used only to separate two or more years linked with one author (author group). If two or more citations are made in one set of parentheses, they should be separated by a semi-colon. If more than one citation for a particular author (author group) is made for the same year, "a", "b", "c", etc. should be added to the year. If citations are made within the normal running text, only the year(s) should be placed in parentheses. The following examples illustrate the required style:

 (Copernicus 1986) (Copernicus & Galilei 1988) (Hubble et al. 1985; Newton et al. 1987; Ptolemaus & Copernicus 1988a, 1988b, 1992) Recently Galilei et al. (1991, 1992) showed that ...

Authors' initials are permitted only in exceptional cases, for example, to distinguish between two authors with the same surname. Each literature citation made in the text should have a corresponding entry in the References at the end of the paper. For frequently cited papers, an abbreviated form of citation is recommended, e.g., Paper I, Paper II (if appropriate) or by the initial letters of the authors' surnames.

The Natbib package provides citation commands that automatically format the citations in the proper format. The command \citet is to be used for textual citations, while the command \citep is to be used for parenthetical citations. Some examples are given below.

 \citet{jon90} Jones et al. (1990) \citep{jon90} (Jones et al. 1990) \citep[see][]{jon90} (see Jones et al. 1990) \citep[see][chap.~2]{jon90} (see Jones et al. 1990, chap. 2)

Multiple citations can be made as usual, by including more than one citation key in the \cite command argument.

 \citet{jon90}, \citet{jam91}, and \citet{li98} Jones et al. (1990), James et al. (1991), and Li (1998) \citep{jon90,jam91} (Jones et al., 1990; James et al. 1991) \citep{jon90,jon91} (Jones et al. 1990, 1991) \citep{jon90a,jon90b} (Jones et al. 1990a,b)

## ADS BibTeX records for citing ASCL and ArXiV entries

A&A Bibtex style now supports the “eprint” field for referring to eprints. Eprint entries may be added to your bibtex databases. Note that the entry Bibtex format now provided by ADS is also compatible:

@ARTICLE{2011ascl.soft07005F,
author = {{Freeman}, P. and {Nguyen}, D. and {Doe}, S. and {Siemiginowska}, A.},
title = “{Sherpa: CIAO Modeling and Fitting Package}”,
journal = {Astrophysics Source Code Library},
year = 2011,
month = jul,
eprint = {ascl:1107.005},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

It is also possible to use the extension “archivePrefix” in BibTeX:

@ARTICLE{2011ascl.soft07005F,
author = {{Freeman}, P. and {Nguyen}, D. and {Doe}, S. and {Siemiginowska}, A.},
title = “{Sherpa: CIAO Modeling and Fitting Package}”,
journal = {Astrophysics Source Code Library},
year = 2011,
month = jul,
archivePrefix = "ascl",
eprint = {1107.005},
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

An ArXiv example:

@ARTICLE{loinard12,
author = {{Loinard}, L. and {Zapata}, L.~A. and {Rodriguez}, L.~F. and
{Pech}, G. and {Chandler}, C.~J. and {Brogan}, C.~L. and {Wilner}, D.~J. and {Ho}, P.~T.~P. and {Parise}, B. and {Hartmann}, L.~W. and {Zhu}, Z. and {Takahashi}, S. and {Trejo}, A.},
title = "{ALMA and VLA observations of the outflows in IRAS 16293-2422}",
journal = {ArXiv e-prints},
archivePrefix = "arXiv",
eprint = {1211.4744},
keywords = {Astrophysics - Solar and Stellar Astrophysics, Astrophysics - Galaxy Astrophysics},
year = 2012,
month = nov,
adsnote = {Provided by the SAO/NASA Astrophysics Data System}
}

After running LaTeX and BibTeX on it, an entry is generated in the .bbl file, which looks like:

\bibitem[{{Freeman et al.}(2011)]{2011ascl.soft07005F}
{Freeman}, P., {Nguyen}, D., {Doe}, S., and {Siemiginowska}, A. 2011
Astrophysics Source Code Library, \eprint{ascl:1107.005}

Or

\bibitem[{{Loinard} {et~al.}(2012){Loinard}, {Zapata}, {Rodriguez}, {Pech}, {Chandler}, {Brogan}, {Wilner}, {Ho}, {Parise}, {Hartmann}, {Zhu}, {Takahashi}, \& {Trejo}}]{loinard12}
{Loinard}, L., {Zapata}, L.~A., {Rodriguez}, L.~F., {et~al.} 2012, ArXiv e-prints [\eprint[arXiv]{1211.4744}]

The aa class now includes the “\eprint” command, which will appear in your final article as a link in both the PDF file and the HTML format.

• Loinard, L., Zapata, L. A., Rodriguez, L. F., et al. 2012, MNRAS, accepted [arXiv:1211.4744]

### Remarks

Please note that it is mandatory to add the eprint number when the entries are:

journal = {Astrophysics Source Code Library} and journal = {ArXiv e-prints}.