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
Narbonne, G.M. Modular Construction of Early Ediacaran Complex Life Forms. Science 2004, 305, 1141–1144.
A journal article with 2 authors
Wang, J.; Genack, A.Z. Transport through Modes in Random Media. Nature 2011, 471, 345–348.
A journal article with 3 authors
Chávez, A.E.; Singer, J.H.; Diamond, J.S. Fast Neurotransmitter Release Triggered by Ca Influx through AMPA-Type Glutamate Receptors. Nature 2006, 443, 705–708.
A journal article with 4 or more authors
Percec, I.; Plenge, R.M.; Nadeau, J.H.; Bartolomei, M.S.; Willard, H.F. Autosomal Dominant Mutations Affecting X Inactivation Choice in the Mouse. Science 2002, 296, 1136–1139.

Books and book chapters

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

An authored book
Schulman, F.Y. Veterinarian’s Guide to Maximizing Biopsy Results; John Wiley & Sons, Inc.: Chichester, UK, 2016; ISBN 9781119226260.
An edited book
Ecological Effects of Water-Level Fluctuations in Lakes; Wantzen, K.M., Rothhaupt, K.-O., Mörtl, M., Cantonati, M., -Tóth, L.G., Fischer, P., Eds.; Developments in Hydrobiology; Springer Netherlands: Dordrecht, 2008; Vol. 204; ISBN 9781402091919.
A chapter in an edited book
Armitage, J. Bacterial Behavior. In The Prokaryotes: Volume 2: Ecophysiology and Biochemistry; Dworkin, M., Falkow, S., Rosenberg, E., Schleifer, K.-H., Stackebrandt, E., Eds.; Springer: New York, NY, 2006; pp. 102–139 ISBN 9780387254920.

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
Andrew, E. New Images Show Sparks Literally Fly When Egg And Sperm Unite 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 Federal Student Aid: Additional Management Improvements Would Clarify Strategic Direction and Enhance Accountability; U.S. Government Printing Office: Washington, DC, 2002;

Theses and dissertations

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

Doctoral dissertation
Thiss, P.J. Effects of Dedicated Academic Support Services on the Persistence Rates of California Community College Student-Athletes. Doctoral dissertation, Northcentral University: Scottsdale, AZ, 2009.

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
Rothenberg, B. Nadal and Federer Steady a Collision Course. New York Times 2017, SP1.

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