How to Cite
When citing DLMF from a formal publication, we suggest a format similar to the following:

[DLMF]
NIST Digital Library of Mathematical Functions. http://dlmf.nist.gov/, Release 1.0.15 of 20170601. F. W. J. Olver, A. B. Olde Daalhuis, D. W. Lozier, B. I. Schneider, R. F. Boisvert, C. W. Clark, B. R. Miller, and B. V. Saunders, eds.
The following BibTeX may be useful: citedlmf.bib.
When referring to a specific item (chapter, section, equation, …), please mention the reference number. For example:
For the gamma function at positive integer argument, see [DLMF, Eq. 5.4.1].
(e.g. using LaTeX: \cite[Eq.~5.4.1]{DLMF}
).
Your readers can then readily locate the item within the book
or online (at http://dlmf.nist.gov/5.4.E1 in this example; see § Permalinks & Reference numbers).
Citations from electronic media (the web, email, …), should, of course, give the URL http://dlmf.nist.gov/, or for a specific item, use the Permalink, such as http://dlmf.nist.gov/5.4.E1. Since the reference number is immediately recognized from the URL as Eq. 5.4.1, it is quickly located in the book.
§ Permalinks & Reference numbers
The direct correspondence between the reference numbers in the printed Handbook and the permalinks used online in the DLMF enables readers of either version to cite specific items and their readers to easily look them up again — in either version!
The following table outlines the correspondence between reference numbers as they appear in the Handbook, and the URL’s that find the same item online. Note the ‘E’, ‘F’ and ‘T’ used to disambiguate equations, figures and tables.
Item Type  Ref. Number  Permalink 

Chapters  5  http://dlmf.nist.gov/5 
Sections  5.4  http://dlmf.nist.gov/5.4 
Subsections  5.4(iii)  http://dlmf.nist.gov/5.4.iii 
Equations  5.4.1  http://dlmf.nist.gov/5.4.E1 
Figures  5.3.1  http://dlmf.nist.gov/5.3.F1 
Tables  5.4.1  http://dlmf.nist.gov/5.4.T1 
For convenience, the permalink can be found in the popup ‘Info box’ associated with each item in the site.