How to Cite CPL in Your Paper : a Complete Guide from Flowcite

Citing sources is an integral part of the research process, as it allows you to credit the author of the ideas you borrowed and expand on their previous research. If you’re a student, academic, or professional researcher, you already know that proper citation keeps you from committing plagiarism—a slippery slope that can result in professional misconduct.

More than avoiding the consequences, submitting your research paper with the proper citation format also increases the likelihood of publication. So, naturally, you’d want to pay close attention to the formatting rules required by your chosen journal. 

While there are many formatting styles out there, for this article, we’re focusing on how to cite CPL style in your research paper. 

What is CPL? 

Constraint Programming Letters (CPL) is an international forum where articles on the topic of constraint programming are published electronically. CPL aims to promote, nurture, and report successful applications and encourage the interlinking of constraint programming ideas to other fields of studies. 

Published CPL papers are relatively short, often less than 6,000 words. They are also freely available online, making it easy for readers around the world to access and read.

CPL accepts unpublished papers in constraint programming containing topics, such as:

  • Applications of existing techniques that highlight the strengths and weaknesses of constraint programming methods.
  • Implementation, design, and evaluation of constraint programming systems.
  • Modelling and representational issues in constraint programming and how they affect solution quality and computation times.
    • This includes comparing constraint programming’s strengths and weaknesses with other techniques in specific case studies.
  • Software engineering aspects of constraint programming.

Similar to other citation styles, there is a distinct required formatting for CPL papers. If you are writing research that has anything to do with constraint programming, you’ll want to understand how to cite CPL style well.

How to code in CPL style

To start writing your paper in CPL format, you first need to learn the required formatting of CPL papers. The recommended way to begin writing your research in CPL format is by using software that can produce a PostScript or PDF output; LaTex is preferred. 

When coding in CPL format, here are the formatting templates you need to keep in mind:    

  • Cpl2e.sty: A CPL LaTeX style.
  • Natbib: Recommended citation file in cpl2e.sty 

Using cpl2e.sty 

When using this format, your paper should begin with a specification of the document class and CPL style file. Here is an example:




Moreover, citing authors should be specified with the “author” macro: 

\author{\name Author One \email author-one-email\\

\addr Author One address line one\\

Author One address line two\\

Author One address line three…


\name Author Two \email author-two-email\\

\addr Author Two address line one\\

Author Two address line two\\

Author Two address line three…}


Citations using natbib

The recommended citation style file, natbib, is included in cpl2e.sty, which supports the citation style with macros such as \citep{} and \citet{}. The basic uses of these two commands are as follows: 

\citet{bar93} => Barrows et al. (1993)
\citet[chap.~6]{bar93} => Barrows et al. (1993, chap. 6)
\citep{bar93} => (Barrows et al., 1993)
\citep{bar93,bar94} => (Barrows et al., 1993, 1994)


Additionally, here are some of the other citation commands you can use throughout your paper.

Command Description
\citet{} Textual citation
\citep{} Parenthetical citation
\citet*{} Similar to \citet, but with multiple authors, all names are printed.
\citep*{} Similar to \citep, but with multiple authors, all names are printed.
\citeauthor{} Prints only the author(s) name
\citeyear{} Prints only the year of publication


Now that you are familiar with the two different formatting styles for your coding, here’s how you can apply the CPL template to your paper.

How to cite CPL style 

The following sections will help you how to properly use the correct CPL format when citing sources in your paper. 

In-Text Citation

In CPL style, citations within the text must include the author’s last name and year. In cases when you are citing three or more authors, you can shorten the citation by only referring to the first author followed by “et al.” 

If the author’s name is essential within the text, the citation only needs the year after the author’s last name enclosed in parentheses: 

Description In-Text Citation
The author’s name is mentioned within the text “Specter (2019) stated that the method of partial discombobulation…”
Regular citation within the text “The method of partial discombobulation is effective (Specter, 2019).”


Additionally, it’s important to note that you should not have a parenthetical statement embedded in a parenthetical statement. Instead, it should be separated by commas like so: 

Wrong format Correct format
“Solar energy helps in reducing electricity cost (as shown by Litt (2020)).”  “Solar energy helps in reducing electricity costs (as shown by Litt, 2020).”


Citing Authors 

When citing authors within your paper, you are expected to include the author’s last name and the year of publication. Here are a few examples:

Description Citing Authors
Citing only one author “Humans are showing great interest in AI-controlled robots (Barrows, 2017)”
Citing multiple authors “The rise of AI-driven technology significantly improves human efficiency (Tanz & Cole, 2015)” 
Citing three or more authors “Quantum technology uses quantum physics to make new things possible (Edwards et al., 2012)” 
Citing two works of the same author “Robots has been developed to help in daily activities (Richmond 2008, 2010)” 


Reference List 

Your paper’s reference section should appear at the end of your article labelled with “Reference” in natbib format. 

Here is how citation in CPL template differs from one material type to another: 

Material Type Format Example
Book Author(s) Name.

Title of Book.

Publisher, City of Publisher, Year of  Publication.

Harvey Edwards.

Dynamic Programming.

University of Chicago Press, Chicago, Illinois, 1995.

Journal Article Author(s) Name.

Title of the article.

Title of Journal, pp. xx-xx, publication year.


Christina Yang. 

Learning from noisy examples.

Cardiothoracic, 2(3):-623,1994.

Forthcoming Publication Author(s) Name.

Title of article.

Title of publication, forthcoming.

Liam Cole.

Statistical aspects of rocket building.

Space Technology, forthcoming.


Note: When citing on your reference list, you should follow the proper breaking of each section. 

Flowcite: Cite CPL Style Correctly

The required formatting of CPL papers can be intimidating and draining for even an experienced academic. Even after reading our guide on how to do it, you might feel a bit lost—but when you use the right tools, it’s easier than you expect. 

If you want to write your paper with the correct citation format, consider using an academic writing suite such as Flowcite—a powerful software that streamlines your citation process and ensures quality outputs.

Flowcite is an all-in-one platform that assists students and researchers across the globe. Our automated reference and citation generator makes the citation process easy, allowing you to spend most of your time researching and writing. Plus, with our LaTex text editor referencing software, you can easily select CPL citation style from over 7,000 citation styles available.

Flowcite empowers you with innovative solutions beyond the citation process as well. Try using the following tools to help you write and publish your paper:

  • Integrated summary generator using Scholarcy to easily identify relevant articles without having to read through them.
  • Proxy access to university libraries for the most comprehensive research platforms.
  • Advanced search engine with access to over 25 million Open Access articles.
  • Premium author and publication services so your research paper is perfectly formatted, peer-reviewed, and sent to the most suitable journal.

Flowcite simplifies the research process, saving you hours of effort. Our software reduces tedious tasks, such as formatting and citation, and instead, allows you to focus on writing a research paper with the highest submission rate for publication.  

Sign up for Flowcite today to cite in CPL style effortlessly! 

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