LaTeX is a specific document preparation system that allows for high-quality typesetting and is especially useful for technical and scientific documentation. The University of Twente is providing access to Overleaf, a collaborative online LaTeX editor. For managing references in Overleaf, the BibTeX extension format is used, known as *.bib. Most reference managers (e.g. Endnote, Mendeley and Zotero) can export references in the BibTeX format. This guide is focussing on BibTeX in Overleaf. Find more information on other forms of LaTeX on the LaTeX Project and TeX Users Group.
- Getting started with BibTeX
BibTeX basics
BibTeX references are stored in a plain text file (the bibliography database file) with file extension *.bib. Save all references in one file (e.g. references.bib) and upload it to your Overleaf project. New references can be easily added to that file in Overleaf by copy and pasting the reference information in BibTeX format. Some databases offer the export of references in this BibTex format. Always check the entries on completeness and consistency. For example, the export from Google Scholar does not include DOI.
Depending on the source (journal article, book chapter, webpage, etc.), the reference in the *.bib file requires a certain format. Each reference starts with @ to indicate the reference type, followed by curly bracket and a unique citation key. Reference information is added and the reference ends by a closing curly bracket. Standard templates for typical reference types are available. For example for a book:
@book{gratzer2014,
title={Practical LaTeX},
author={Gr{\"a}tzer, George},
year={2014},
publisher={Springer}
}The unique citation key is used for in-text references in the *.tex file with the \cite{} command (e.g. \cite{gratzer2014}). If multiple sources are cited, use a comma to separate the citation keys \cite{gratzer2014, citation2, citation3}). The bibliography can be added anywhere in the *.tex file (usually at the end) by using the command \bibliography{references.bib}. Before adding the bibliography, indicate the reference style in the *.tex file with \bibliographystyle{stylename}, e.g. {apalike} for APA and {IEEEtran} for IEEE. The order in which the references appear, depend on the reference style. Find standard BibTex Bibliography Styles here.
BibTeX and reference managers
It is possible to convert references from your reference manager to BibTeX format. This can also be done when a database does not support download in BibTeX format. In such cases, download the references to your reference manager and then convert them into BibTeX with the export function. Always check the entries in the *.bib file for completeness and assigned reference types. Simply upload the exported file in the project to use it.
If you want to use BibTex extensively in Overleaf, you may want to consider the reference managers Mendeley or Zotero. Use the Mendeley or Zotero plugin to insert your references directly.
- Troubleshooting
In case of errors, read the warning. It usually indicates well what the problem is. The “undefined citation” is a very common warning wherein \cite{} is showing up as question marks (?). Follow this checklist to solve the problem:
- Check if the right *.bib is specified for /bibliography{} and no errors in spelling are made for /cite{}. Only entries spelled as in the *.bib file will appear in the main text and bibliography. It is case sensitive and does not always recognize unusual characters or spaces in file/folder names during the compiling process.
- Check if the bibliography style is a standard or if you need to upload a new style.
- Sometimes it just does not work due to formatting issues. Try adding clearing the document cache by selecting the “recompile from scratch” from the green compile button. Alternatively use the command /typeout{} before the /bibliography{}.
Contact your faculty’s information specialist for any questions on troubleshooting via the button at the bottom of this page.
- BibTeX guides and instruction videos
Online guides
Instruction videos
- BibTeX training
The university offers a 3-hour workshop to provide a general introduction to LaTeX, including (cross)referencing and citations: UTwente course LaTeX