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
Nossal, G.J. A Purgative Mastery. Nature 2001, 412, 685–686.
A journal article with 2 authors
Gan, J.; Appenzeller, T. 2013 Visualization Challenge. Introduction. Science 2014, 343, 599.
A journal article with 3 authors
Smolyaninov, I.I.; Hung, Y.-J.; Davis, C.C. Magnifying Superlens in the Visible Frequency Range. Science 2007, 315, 1699–1701.
A journal article with 4 or more authors
Kofler, N.; Collins, J.P.; Kuzma, J.; Marris, E.; Esvelt, K.; Nelson, M.P.; Newhouse, A.; Rothschild, L.J.; Vigliotti, V.S.; Semenov, M.; et al. Editing Nature: Local Roots of Global Governance. Science 2018, 362, 527–529.

Books and book chapters

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

An authored book
Turner, J.R.; Durham, T.A. Integrated Cardiac Safety: Assessment Methodologies for Noncardiac Drugs in Discovery, Development, and Postmarketing Surveillance; John Wiley & Sons, Inc.: Hoboken, NJ, 2008; ISBN 9780470411292.
An edited book
Simms, C. Pedestrian and Cyclist Impact: A Biomechanical Perspective; Wood, D., Ed.; Solid Mechanics and Its Applications; Springer Netherlands: Dordrecht, 2009; Vol. 166; ISBN 9789048127429.
A chapter in an edited book
DeHaven, W.I.; Conner, D.P. The Effects of Food on Drug Bioavailability and Bioequivalence. In FDA Bioequivalence Standards; Yu, L.X., Li, B.V., Eds.; AAPS Advances in the Pharmaceutical Sciences Series; Springer: New York, NY, 2014; pp. 95–118 ISBN 9781493912513.

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
Fang, J. To Save Energy, Blind Cavefish Got Rid of Their Circadian Rhythm 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 Space Industrialization Act of 1980; U.S. Government Printing Office: Washington, DC, 1980;

Theses and dissertations

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

Doctoral dissertation
McFarland-Mancini, M. Prolactin Production by Human Breast Adipose Tissue and Adipocytes. Doctoral dissertation, University of Cincinnati: Cincinnati, OH, 2006.

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
Eligon, J. The Fight Card Often Features the Race Card. New York Times 2017, D1.

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