How to format your references using the Challenges citation style

This is a short guide how to format citations and the bibliography in a manuscript for Challenges. For a complete guide how to prepare your manuscript refer to the journal's instructions to authors.

Using reference management software

Typically you don't format your citations and bibliography by hand. The easiest way is to use a reference manager:

PaperpileThe citation style is built in and you can choose it in Settings > Citation Style or Paperpile > Citation Style in Google Docs.
EndNoteFind the style here: output styles overview
Mendeley, Zotero, Papers, and othersThe style is either built in or you can download a CSL file that is supported by most references management programs.
BibTeXBibTeX syles are usually part of a LaTeX template. Check the instructions to authors if the publisher offers a LaTeX template for this journal.

Journal articles

Those examples are references to articles in scholarly journals and how they are supposed to appear in your bibliography.

Not all journals organize their published articles in volumes and issues, so these fields are optional. Some electronic journals do not provide a page range, but instead list an article identifier. In a case like this it's safe to use the article identifier instead of the page range.

A journal article with 1 author
Haigwood, N.L. HIV: Tied down by Its Own Receptor. Nature 2015, 519, 36–37.
A journal article with 2 authors
Pedraza, J.M.; Paulsson, J. Effects of Molecular Memory and Bursting on Fluctuations in Gene Expression. Science 2008, 319, 339–343.
A journal article with 3 authors
Maiorano, D.; Moreau, J.; Méchali, M. XCDT1 Is Required for the Assembly of Pre-Replicative Complexes in Xenopus Laevis. Nature 2000, 404, 622–625.
A journal article with 4 or more authors
Norell, M.; Ji, Q.; Gao, K.; Yuan, C.; Zhao, Y.; Wang, L. Palaeontology: “modern” Feathers on a Non-Avian Dinosaur. Nature 2002, 416, 36–37.

Books and book chapters

Here are examples of references for authored and edited books as well as book chapters.

An authored book
Basener, W.F. Topology and Its Applications; John Wiley & Sons, Inc.: Hoboken, NJ, 2006; ISBN 9780470067949.
An edited book
Bioluminescence: Fundamentals and Applications in Biotechnology - Volume 1; Thouand, G., Marks, R., Eds.; Advances in Biochemical Engineering/Biotechnology; Springer: Berlin, Heidelberg, 2014; Vol. 144; ISBN 9783662433843.
A chapter in an edited book
Jankowski, D.; Jackowski, K. Evolutionary Algorithm for Decision Tree Induction. In Computer Information Systems and Industrial Management: 13th IFIP TC8 International Conference, CISIM 2014, Ho Chi Minh City, Vietnam, November 5-7, 2014. Proceedings; Saeed, K., Snášel, V., Eds.; Lecture Notes in Computer Science; Springer: Berlin, Heidelberg, 2014; pp. 23–32 ISBN 9783662452363.

Web sites

Sometimes references to web sites should appear directly in the text rather than in the bibliography. Refer to the Instructions to authors for Challenges.

Blog post
O`Callaghan, J. These Are Some Of Rosetta’s Last Stunning Images Of Comet 67P Available online: (accessed on 30 October 2018).


This example shows the general structure used for government reports, technical reports, and scientific reports. If you can't locate the report number then it might be better to cite the report as a book. For reports it is usually not individual people that are credited as authors, but a governmental department or agency like "U. S. Food and Drug Administration" or "National Cancer Institute".

Government report
Government Accountability Office U.S.-Korea Fighter Coproduction Program; U.S. Government Printing Office: Washington, DC, 1990;

Theses and dissertations

Theses including Ph.D. dissertations, Master's theses or Bachelor theses follow the basic format outlined below.

Doctoral dissertation
Watson, D.J. How the Lead Systems Integrator Experience Should Enhance Efforts to Rebuild the Defense Acquisition Workforce. Doctoral dissertation, George Washington University: Washington, DC, 2010.

News paper articles

Unlike scholarly journals, news papers do not usually have a volume and issue number. Instead, the full date and page number is required for a correct reference.

New York Times article
Sophia Kishkovsky; Compiled by Arts, Briefly; 2 Missing Russian Works Recovered. New York Times 2006, B8.

In-text citations

References should be cited in the text by sequential numbers in square brackets:

This sentence cites one reference [1].
This sentence cites two references [1,2].
This sentence cites four references [1–4].

About the journal

Full journal titleChallenges
ISSN (online)2078-1547

Other styles