How to format your references using the Proceedings of the National Academy of Sciences of the United States of America citation style

This is a short guide how to format citations and the bibliography in a manuscript for Proceedings of the National Academy of Sciences of the United States of America (PNAS). 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
R. Fortey, Evolution. The Cambrian explosion exploded? Science 293, 438–439 (2001).
A journal article with 2 authors
P. L. Larsen, C. F. Clarke, Extension of life-span in Caenorhabditis elegans by a diet lacking coenzyme Q. Science 295, 120–123 (2002).
A journal article with 3 authors
V. K. Iyengar, H. K. Reeve, T. Eisner, Paternal inheritance of a female moth’s mating preference. Nature 419, 830–832 (2002).
A journal article with 6 or more authors
W. Liu, et al., PHF8 mediates histone H4 lysine 20 demethylation events involved in cell cycle progression. Nature 466, 508–512 (2010).

Books and book chapters

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

An authored book
G. Camarillo, M. A. García-Martín, The 3G IP Multimedia Subsystem (IMS) (John Wiley & Sons, Ltd, 2006).
An edited book
M. Riopel, Z. Smyrnaiou, Eds., New Developments in Science and Technology Education, 1st ed. 2016 (Springer International Publishing, 2016).
A chapter in an edited book
L. Zhao, “Forging a Harmonious Relationship Among the Ethnic Groups” in China in the Xi Jinping Era, S. Tsang, H. Men, Eds. (Springer International Publishing, 2016), pp. 97–121.

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 Proceedings of the National Academy of Sciences of the United States of America.

Blog post
E. Andrew, New Material Could Be Both A Solar Cell And Display Screen. IFLScience (2014) (October 30, 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, “Screening Partnership Program: TSA Should Issue More Guidance to Airports and Monitor Private versus Federal Screener Performance” (U.S. Government Printing Office, 2012).

Theses and dissertations

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

Doctoral dissertation
M. Kim, “Adult ESL Korean readers’ responses about their reading in L1 Korean and L2 English,”  University of Arizona,  Tucson, AZ. (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
C. Talmadge, A Military Budget Without a Plan. New York Times, A23 (2017).

In-text citations

References should be cited in the text by sequential numbers in parentheses:

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 titleProceedings of the National Academy of Sciences of the United States of America
AbbreviationProc. Natl. Acad. Sci. U. S. A.
ISSN (print)0027-8424
ISSN (online)1091-6490

Other styles