# Natbib package error? Bibliography not compatible with author-year citations

I'm trying to write an article for a journal using it's LaTeX class and there seems to be an issue with the bibliography.

I'm getting the following error message:

Package natbib Error: Bibliography not compatible with author-year citations.

I think that the LaTeX class loads the natbib package by default.

I know that natbib is a special package for bibliography, but that's all I know about it, and I don't even know how to use it. All I want to do is just be able to compile my LaTeX code without getting any errors.

I've been searching for quick solutions on the internet, but I'm being unable to solve the problem. I tried a couple of things such as replacing the new natbib style file with an older version (as suggested somewhere on the internet), but nothing seems to work.

Also, I'm pretty sure I'm formating the references according to the journal's instructions, so I don't know what the problem might be.

If I enter return when the errors occurs, the MikTeX application continues compiling the code and the PDF file is generated without any problems. Anyway, I don't want the natbib error to appear because I don't know if the journal will accept the code with this error.

Here's some code I'm using:

\begin{thebibliography}{0}
\bibitem{author's last name:year}
author's last name, author's first name initial.
Author's article.''
\textit{journal} (year)

\bibitem{author's last name:year}
author's last name, author's first name initial.
\textit{book title}, edition, p. page number.
place of publication: publisher, year.

\end{thebibliography}


Extra information: In the text, I'm able to cite references without any problems by using \citep. If I use \cite, some text disappears when the code is compiled, and \citet won't work.

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It is important to know which document class and which bibliography style you are using. –  Kurt Aug 27 '12 at 0:14
Sorry, how do I check the bibliography style? –  Juan Aug 27 '12 at 0:16
@Juan natbib is really designed to be used with bibtex. So you shouldn't be entering bibliography entries by hand, but into a separated .bib file which bibtex uses to generate the bibliography items. See the Bibliographies section of the answer to this question: What TeX software to write technical papers with. –  Alan Munn Aug 27 '12 at 0:19
@Juan: do you use a macro like \bibliographystyle{alpha}? Then alpha names the style. Do you have no information for this in your Journals advice? Which Journal (normally they have special classes and styles, which are important to know!)? –  Kurt Aug 27 '12 at 0:25
In my code there is no "\bibliographystyle{...}". At the top of MikTeX window it says "pdfLaTeX+MakeIndex+BibTeX". –  Juan Aug 27 '12 at 0:39

Storing your references in a bibtex database and using bibtex would be the best option. However, if you want to edit manually your bibliography you have to use the appropriate format for natbit.

The format of the bibliography entries for natbibt is

\bibitem[NameShort(year)NameLong]{citation-label}
author's last name, author's first name initial.
Author's article.''
\textit{journal} (year)


NameShort can be use to list only the first name an the et al. abbreviation. NameLong is the full list of authors. NameShort is what is used in the majority of cite commands.

Thus, you can modify you \bibitem entry as follows

\bibitem[Name1 et~al(2012)Name1, Name2, Name3]{cite-label}
...


or as follows

\bibitem[Name1, Name2, and Name(year){cite label}]
...
`
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