Citations and References

Last updated on 2026-07-26 | Edit this page

Estimated time: 30 minutes

Overview

Questions

How do I add bibliographic references to my document?
How do I format my references in LaTeX?
How do I cite references in my document?

Objectives

Learn how to use a reference database to manage references in LaTeX documents.
Explore different ways of citing references in our document.

Citations and References

For bibliographic citations, while you can include references sources directly in our document, usually you will get that information from one or more external files. Such a file is a database of references, containing the information in a processing-friendly format (which is called BibTeX). Using one or more reference databases lets you re-use information and avoid manual formatting.

Settings

TeXstudio offers several backend options for handling BibTeX files. For the purposes of this workshop, we’ll use Biber. Open TeXstudio and go to Options > Configure TeXstudio. In the configuration dialog, select Build from the left-hand panel. Under Default Bibliography Tool, open the drop-down menu and select Biber.

Reference Databases (BiBTeX)

Reference databases are normally referred to as BiBTeX files, and have the extension .bib. They contain one or more entries, one for each reference, and within each are a series of fields.

Create a new file in your project called sample-references.bib and add the following content:

BIBTEX

@article{Thomas2008,
	author  = {Thomas, Christine M.},
	title   = {The Fascinating World of Penguins},
	journal = {Penguin Chronicles},
	date    = {2008},
	pages   = {7009-7024},
}

@book{Graham1995,
	author    = {Graham, Richard L. and Harris, Lisa A.},
	title     = {The Humble Paperclip},
	subtitle  = {Master of the Modern Office},
	publisher = {Scranton Press},
	year      = {1995},
}

This is an example of a BiBTeX file that contains a reference for an article and another for a book. Each entry type begins with the @ symbol, followed by the entry type (e.g. article), with all information enclosed in curly braces {}. The first element (e.g. Thomas2008) inside the curly braces is the reference key, which is used to cite the entry in the document.

Beyond the types already mentioned, other commonly supported types include manual, conference, proceedings, and techreport. If none of the available types are suitable, misc can be used as a fallback, however this may lead to incomplete references and formatting inconsistencies.

The various fields are given in key-value format. Which fields are required depends on the entry type and bibliography style. Common fields are author, title, publisher, year, edition, journal, volume, and pages, among many others.

Callout

You might notice that in the author field, surname and given name and each entry (author) is separated by the word and. This is essential: the format of the output needs to know which author is which. When using biblatex this applies also to the fields publisher and location, in which you can also have many values.

You might also notice that in the article title, some entries are in an extra set of braces. This is to prevent any case-changing that might be applied to the title.

The BibTeX Format

Editing BiBTeX files by hand can be difficult and tedious. A number of tools exist to help you manage your reference files. You can find a list of suggested tools in the references section.

For the purposes of this workshop, we’ll use biblatex, but feel free to explore other options (e.g. natbib) on your own.

Check to make sure that your main.tex file is in the same directory as your sample-references.bib file.

At the top of our main.tex file, we’ll add a line to import biblatex:

LATEX

\usepackage[style=authoryear]{biblatex}
\addbibresource{sample-references.bib}

Do not forget to write the suffix of your referencing file, too (.bib).

Then, at the bottom of your main.tex file, add the following lines:

LATEX

\printbibliography

And… nothing? Right, because we haven’t cited anything in our document yet. Let’s add a citation:

LATEX

\section{Reference Databases}

We can \kw{cite references} from our bibliography.

We can cite the article by Thomas (e.g. with `\textbackslash autocite\{Thomas2008\}`).

You should see that the citation appears in the text ((Thomas et al. 2008)), and the reference now appears at the end of the document. is a command that automatically chooses the citation style for you.

Some additional commands that are available in biblatex:

\cite{key} or \cite{key1, key2}: Cite the reference with the given key
\parencite{key}: Cite the reference with parentheses around it, e.g. (Author, Year).
\textcite{key}: Cite the reference as part of the text, e.g. Author (Year)
\autocite{key}: Automatically choose the citation style.
\smartcite{key}: Automatically choose the citation style, but with more control.
\footcite{key}: Cite the reference in a footnote.

A plain citation looks like this \cite{Graham1995}, while multiple citations look like this \cites{Graham1995}[see][p. 42]{Thomas2008}. We already used autocite, but we can also use the similar smartcite \smartcite{Graham1995}. The benefit with smartcite is that you can setup that e.g. all references should go into a footnote. You can continue using smartcite when you are in a footnote and it will then detect that there is no need for creating another footnote but behaving like autocite.

Furthermore you can use more commands to get the author, title or the date of the publication directly into your document:

\citeauthor{Graham1995}: Graham and Harris
\citetitle{Graham1995}: “The Humble Paperclip”
\citeyear{Graham1995}: 1995

The outcome and display depends on your style.

If you want to have all entries of your referencing file in your bibliography, you can either go with \cite{key1,key2,.....} for all entries or you type \cite{*}. This will print all entries first in your text section and puts them into the bibliography. You can also go with \nocite{*} then the reference is only internally called and put into the bibliography.

It is always good to tidy up your .bib-file and use the fields accordingly. In case you want to omit certain fields in your bibliography you can do so on the fly:

LATEX

\AtEveryBibitem{
  \clearfield{url}
  \clearfield{month}
  \clearfield{note}
  \clearfield{isbn}
  \clearname{translator}
  \clearlist{language}
}

With this command you will delete the content of the fields in the bibliography. Note, that there is \clear*field*, \clear*name* and \clear*list*.

Callout

There are many different bibliography styles available, and you can find a list of them at CTAN. Check if one of those bibliography and citation styles meets your requirements. If you want to finetune an existing one we suggest to take a look at biblatex-ext.

Instructor Note

Inline instructor notes can help inform instructors of timing challenges associated with the lessons. They appear in the “Instructor View”

Challenges

Challenge

Challenge 1: Add another reference, then delete it.

Try adding the following reference to your sample-references.bib file:

BIBTEX

@book{Huff1954,
  author    = {Huff, Darrell},
  title     = {How to Lie with Statistics},
  publisher = {W. W. Norton \& Company},
  year      = {1954},
}

Then, add a citation to this reference in your document. Try a couple different styles of citation commands. Then, once you have it working, delete the reference and re-compile your document. What happens?

Show me the solution

You might expect removing the reference to either error or remove the citation from the text, but it doesn’t - instead we get a placeholder in the text and a warning in the log. A missing reference is not so critical an error that we can’t render the document, but we should probably fix it.

Challenge

Challenge 2: What’s wrong with this?

We have the following reference in our document:

BIBTEX

@misc{mikolov2013,
	title         ={Efficient Estimation of Word Representations in Vector Space},
	author        ={Mikolov, Tomas and Chen, Kai and Corrado, Greg and Dean, Jeffrey},
	year          ={2013},
	eprint        ={1301.3781},
	archivePrefix ={arXiv},
	primaryClass  ={cs.CL},
	url           ={https://arxiv.org/abs/1301.3781},
}

We are using biblatex to manage our references, and we identify this reference in the text like this:

LATEX

The Word2Vec algorithm \autocite{mikolov} is a popular method
for generating word embeddings.

When we compile our document, we see the following error:

OUTPUT

The Word2Vec algorithm (mikolov) is a popular
method for generating word embeddings.

What’s wrong with this reference? How can we fix it?

Show me the solution

We are referencing the key mikolov in our document, but the key in our BibTeX file is mikolov2013. We need to update our citation command to \autocite{mikolov2013}. Note that LaTeX still compiles the document, but it gives us a warning that the reference is missing and uses the key as a placeholder. You might use this to temporarily mark a reference that you haven’t added yet, just be sure to clear all of your warnings before finalizing your document.

Challenge

Challenge 3: What’s the problem with this?

We include the following reference in our document:

BIBTEX

@article{bentham2011,
	author = {H. Muller, Rainer and Shegokar, Ranjita and M. Keck, Cornelia},
	title = {20 Years of Lipid Nanoparticles (SLN & NLC): Present State of Development & Industrial Applications},
	journal= {Current Drug Discovery Technologies},
	year = {2011},
	volume = {8},
	number = {3},
	pages = {207--227},
	doi = {https://doi.org/10.2174/157016311796799062},
	publisher = {Bentham Science Publishers},
}

We are using biblatex and cite this reference in the text as follows:

LATEX

\autocite{bentham2011} provide a good overview over
nanoparticles over the last 20 years.

What happens when compiling this document? What is wrong with the reference, and how can it be fixed?

Show me the solution

The issue in this reference is caused by a special character (& in the title field). In LaTeX the ampersand & is reserved for alignment, so it must be escaped (\&)in normal text.

If special characters are not escaped properly, LaTeX produce unexpected output or may fail to compile. In some cases, this can also corrupt auxiliary files (such as .aux or .bbl), preventing the document from rendering as expected. If problems persist after correcting the reference, a common solution is to delete all intermediate files and recompile the document from scratch. Deleting them forces a clean rebuild.

Corrected bib entry:

BIBTEX

@article{bentham2011,
	author = {H. Muller, Rainer and Shegokar, Ranjita and M. Keck, Cornelia},
	title = {20 Years of Lipid Nanoparticles (SLN \& NLC): Present State of Development \& Industrial Applications},
	journal= {Current Drug Discovery Technologies},
	year = {2011},
	volume = {8},
	number = {3},
	pages = {207--227},
	doi = {https://doi.org/10.2174/157016311796799062},
	publisher = {Bentham Science Publishers},
}

Challenge

Challenge 4: APA Style and coloring.

Again we have the example:

LATEX

The Word2Vec algorithm by \textcite{mikolov2013} is a popular
method for generating word embeddings.

Change the bibliography style to the American Psychological Association (APA) style by replacing the default style option. What differences do you notice?

As a bonus challenge, try to colorize your citation links in blue.

Give me a hint

The hyperref package is used to manage links in LaTeX. To colorize links, you first need to enable colored links and then set the desired color using the \hypersetup{} command.

Show me the solution

LATEX

\documentclass{article}

\usepackage[style=apa]{biblatex} % APA style
\addbibresource{sample-references.bib}
\usepackage{hyperref}

\hypersetup{
	colorlinks = true, % enable coloring
	citecolor = blue,  % change color
}


\begin{document}

The Word2Vec algorithm by \textcite{mikolov2013} is a popular
method for generating word embeddings.


\printbibliography

\end{document}

The bibliography style also influences which information is printed. Due to the change to the APA style, the values of the fields archivePrefix, primaryClass, and eprint are no longer printed.

Key Points

References are stored in a reference database, separate from the LaTeX document.
BibTeX files are used to store references in a processing-friendly format and have the extension .bib.
There are multiple libraries available to manage references in LaTeX documents, including biblatex.
We can use the \cite command or one of its variants to cite references in our document.