Although the Friends of the SEP Society is distributing PDFs of SEP entries to its members, the proper way to cite an SEP entry is to cite the HTML source from which the PDF was generated, namely, the HTML version publicly located and freely accessible on the web. There are no differences in content between the PDF and HTML versions of SEP entries and so for purposes of citation, passages in the PDF version have exact counterparts in the HTML version. However, there are some formatting differences between the HTML and PDF versions that members of the Friends of the SEP Society should be aware of. See especially item 2 below.

1. Cite the URL of the Corresponding HTML Version. The citation URL of the HTML version is printed at the top of the PDF title page. We encourage our readers to use that string for citation purposes. So, for example, the entry on Turing Machines might be cited as follows:

   Barker-Plummer, D., 2009, “Turing Machines,” Stanford Encyclopedia of Philosophy (Spring 2009 Edition), Edward N. Zalta (ed.), URL = <https://plato.stanford.edu/archives/spr2009/entries/turing-machine/>.

   The URL string used at the end is the one located at the top of the PDF.

2. Identify Passages by Section Not by Page. When referencing, in your own text, a passage within the PDF version of an SEP entry, we strongly encourage you to identify that passage by Section and Subsection (and by paragraph number or paragraph opening phrase, if more exactness is required), rather than by page number. This makes it easier for those who don't have access to the PDF to find the passage being referenced. The HTML versions of SEP entries are not paginated (when viewed in a browser), and when you print them, their pagination varies according to the font type and font size the user has set as the default for his/her browser. By contrast, our PDFs have a fixed font type and size, and fixed linewidth, and are therefore paginated even when viewed online. This makes it tempting for scholars to cite page numbers of the PDF when referencing particular passages in an entry. However, we strongly discourage our members from citing the page numbers of the passages they are quoting or referencing. By citing page numbers, members make it extremely difficult for those who do not have access to the PDF version to locate the passage in question. Non-members only have access to the unpaginated HTML version of the archived edition of the SEP entry you are referencing (which is freely available on the web), and so it will be difficult for them to determine which section of the HTML corresponds to a given page in the PDF.

3. PDFs Correspond to Archive Versions Not Active Versions. The PDFs in our database correspond only to those SEP entries that appear in one of the recent quarterly SEP Archives. We do not create PDF versions of active SEP entries, i.e., we do not create PDF versions of entries in the dynamic section of the SEP which are constantly undergoing changes. The reason is that we want to encourage our readers to cite only entries whose content has been fixed and which will not change. Since the content of the entries in our Archives is fixed, they are suitable for citation. But the entries in the dynamic portion of the SEP are not suitable for citation, for they change frequently. If an entry has just been published for the first time, or an update has been recently published, readers should wait until the entry has been archived in one of the four quarterly Archives. We create a new Archive on March 21, June 21, September 21, and December 21 of each year.

4. PDFs Begin with Spring 2009 Archive. We do not have the resources to create PDF versions of the entries in all our previous archives. Instead, we are beginning with the Spring 2009 Edition (March 21, 2009). Of course, our readers are free to cite any (earlier) archived version of the SEP entry in question. But it may be that the “best practice” for scholarly academic citation is to strive to cite the earliest version of the entry found in our Archives that matches the version of the entry you want to cite, since the date which the material was first published may have consequences for future scholars. Information about the earliest version of the entry that matches the version you want to cite can be found online, by following the Cite This Entry button at the top left corner of the HTML version of every SEP entry.