A manual for writers of research papers, theses, and dissertations, 7th edition - Kate L. Turabian 2007

Online databases
Notes-bibliography style: citing specific types of sources
Part II. Source Citation

For citation of journal articles published in online databases, see 17.2.7. To cite documents or records from other types of online databases in a note, give the author and title of the document (if available), the name of the database (in roman type), the URL, and the date you accessed the material. In your bibliography entry, list the database as a whole, with the URL for the main page and without an access date. Note that a URL alone is not sufficient; you must provide the full facts of publication, as far as they can be determined, so that a reader can search for the source even if the URL changes. For dissertations in online databases, see 17.6.1.

N: 1. Pliny the Elder, The Natural History, ed. John Bostock and H. T. Riley, in the Perseus Digital Library, http://www.perseus.tufts.edu/cgi-bin/ptext?lookup=Plin.+Nat.+1.dedication (accessed March 31, 2006).

B: Perseus Digital Library. http://www.perseus.tufts.edu/