references and citations

For NREL publications, use the Chicago Manual of Style when you document references and use in-text citations. NREL prefers author-date citations (e.g., Smith et al. 2021) with a full references list at the end of the document, rather than numbered footnotes or endnotes.

Reference formatting can get tedious, but keep in mind that the ultimate goal is to clearly present relevant information so that readers can easily locate the sources used. Do the best that you can with the information you have.

Following are examples of commonly cited publication types:

NREL Technical Report
Last, First, First Last, and First Last. Year. Report Title. Golden, CO: National Renewable Energy Laboratory. NREL/TP-XXXX-XXXX. URL [with hyperlink].

Other Technical Reports
Last, First, First Last, and First Last. Year. Report Title. City, State: Publisher. Pub # if available. URL [with hyperlink].

Journal Article
Last, First, First Last, and First Last. Year. “Article Title.” Journal Name Volume # (Issue #): Page #. URL or DOI [with hyperlink].

Conference Paper/Presentation
Last, First, First Last, and First Last. Year. “Paper Title.” Presented at [conference name/location/dates as available]. [Author organization, location, and publication number if available.] URL or DOI [with hyperlink].

Webpage (with authors)
Last, First, First Last, and First Last. Year. “Website Title.” Website name or publisher. Accessed date (e.g., “Accessed January 1, 2021”). URL [with hyperlink].

Webpage (no authors)
Website name or publisher. Year. “Website Title.” Accessed date. URL [with hyperlink].

News Article (online or in print)
Last, First, First Last, and First Last. Year. “Article Title.” News Outlet. Full publish date or access date if publication date not available. URL if available [with hyperlink].

Fact Sheet
Last, First, First Last, and First Last. Year. “Fact Sheet Title.” City, State: Publisher. URL [with hyperlink].

Book
Last, First, First Last, and First Last. Year. Book Title. Publisher.

Book Chapter
Last, First, First Last, and First Last. Year. “Chapter Title.” In Book Title. Edited by First Last (if applicable), page numbers. Publisher.

Thesis or Dissertation
Last, First. Year. “Title.” Ph.D. dissertation/Master’s thesis, University Name.

Personal Communication
Often, mentioning the person’s name in the text is sufficient (“According to John Smith, CEO of XYZ …").

Last, First. Year. Personal communication. Title, Organization Affiliation.

Patent
Last First, First Last, and First Last. Year. Patent Title. Patent number (include country code, the word “Patent,” and patent number with retained commas—for example, US Patent 3,597,875), filed [month, day, year], and issued [month, day, year].

Government Documents
For information on how to cite government documents, including bills and resolutions, court decisions, and congressional hearings, see Bowdoin College’s Quick Guide for Government Documents.

Datasets
Guidance for how to cite datasets can be found within individual dataset entries in the NREL Data Catalog.

Datasets external to NREL can be cited like webpages.

In the references list, include up to 10 author names. If there are more than 10 authors, list the first 6 followed by “et al.” For in-text citations, include up to three names (Smith, Johnson, and Cook 2021). If there are more than three authors, list the first author’s name followed by “et al.” (Smith et al. 2021). Note that “et al.” does not need to be italicized.

If there is more than one reference entry with the same author list and the same publication year, use “a,” “b,” etc. after the year to distinguish the references in the in-text citations (e.g., Smith 2025a).

If there is no year for a published work, use “n.d.” (“no date”) in place of the year. Multiple works with no date and the same author list should use “n.d.-a,” “n.d.-b,” etc. to distinguish.

Place works that you use or recommend for further reading (but do not cite in the text) in a bibliography.

If you are preparing a manuscript for a publisher other than NREL, follow that publisher's preferred reference style. The best place to find this information is on the publisher’s website, typically under an “Information for Authors” section.

See the NREL Library website for information about Zotero and EndNote citation tools.