Occasionally you will come across documents that lack basic publication details. In these cases, it is necessary to indicate to your reader that these are not available. A series of abbreviations can be used and are generally accepted for this purpose:
No date: use [n.d.]
No place (sine loco): use [s.l.]
No publisher: use [s.n.]
Not known: use [n.k.]
For web pages it is often necessary to look beyond the page you are referencing to the ‘Home Page’ for the whole site or at a link such as ‘About Us’ from that home page. Dates are often given at the bottom of web pages.
If there is no date for a source, use the author name and [n.d.].
Example: in text citation
(McCullough, [n.d.])