A classical or religious work is cited as either a book or a webpage, depending on what version of the source you are using. For example, an online version of the Qur’an would be cited using the webpage reference format, but a book version of Plato’s Republic—whether it be a print book or an ebook—would be cited using the book reference format. It’s pretty straightforward!
There are some special considerations to bear in mind for retrievability purposes, however, such as missing reference information for these works. Specifically, the original author and/or publication date of a classical or religious work might be unknown or disputed, in which case you should cite the work as if it has no author and use the date of republication for the version you’re citing, if available. In other words, the title of the work should be placed in the author position, followed by the republication date in parentheses (see the New American Bible and the Srimad Bhagavad-Gita examples later in this post).
When the original publication date of a republished work is known, add it in parentheses at the end of the reference list entry after the phrase “Original work published” (see the Alighieri reference in this post). For ancient works, place “B.C.E.” (short for “before the common era”) after the year. If the date is an approximation, place “ca.” (short for “circa”) before the year (or years if a date range is provided rather than a single year; see the Epic of Gilgamesh reference later in this post).
The translator, if known, should be listed in parentheses after the title, as shown in the Rumi and Alighieri references later in this post.
When directly quoting a classical or religious work in the text, the seventh edition Publication Manual says to use “canonically numbered parts common across editions (e.g., books, chapters, verses, lines, cantos)” (p. 303) instead of page numbers.
If you are using multiple versions of the same source, such as different translations, create a separate reference list entry for each version. However, separate entries are not needed for different formats of the same work (e.g., print and electronic copies). Both print and electronic versions contain identical text, so cite only one version.