Afternoon anxiety attacks are affecting academics agonised over an absence of authority for e-book citations. Behind this nervousness reside conservative attitudes about why have these e-books at all if you cannot quote them accurately in a bibliography. The news, meanwhile, is that the horse has bolted.
One institution has supplied guidelines with the following example of a rule and citation model for a source accessed via Kindle, i.e. a Kindle (or other) location, using Turabian 17.7.1 : “Citation of e-Book Sources: There are a number of electronic book sources now available for general use and some materials only exist in that format. When citing an electronic book of e-Book the reference must contain the actual type or model of e-Book being used (Amazon Kindle, Microsoft, Sony, etc.) and the location number of the quote (since actual page numbers are not created). For example: 1D. Brent Laytham, ed., God Does Not...: Entertain, Play Matchmaker, Hurry, Demand Blood, Cure Every Illness (Grand Rapids: Brazos Press, 2008), Kindle e-book, locations 552–53.
“In addition students must be aware that a professor may request to see the device and examine the quotation and that the student must be able to comply with this request.”
As well, it is worth knowing about this direction, from the same document: “Online and Internet Sources: All online and internet source examples will be guided by Turabian 17.7.1. It must be remembered that a URL will not necessarily take the reader back to the original article (if it was generated by a database for instance), and that they need to retain a printed copy or a electronic copy of the item(s) that can be easily produced in case the source or citation is called into question.”
I would give you the actual link to these guidelines, but since the time I found them this year it has dropped off the internet. The fact that it has done so is another growing issue in this area of technology and bibliography. What to do with online books and articles that have been cited but no longer exist online? How do we cite a scholar who no longer exists because his words have been removed from public view? The professor has no proof that their student is quoting accurately, or even that it may not have been all made up by the student. At least with hardcopy there are normally enough copies shelved in the universe for the professor to confirm their student’s in-depth reading.
This and other in-house style guides are using a combination of Turabian and commonsense. In the absence of any guideline, the sensible thing is to follow the existing pattern of citations in the approved guidelines, using minimum space to record everything pertinent. No doubt e-book formats will be invented with new and even more wonderful ways of page-numbering the text. As with so much in digital, the rulemakers' hesitancy to apply definitive rules is influenced by the unpredictability and variety of formats that keep coming out. Some of us watch for the next edition of The Chicago Manual of Style, Turabian &c. in the hope that definitive directions for e-books will be supplied. But we are not holding our breath. The process is necessarily conservative.