There will be instances where some of the information that you need to reference an item proves elusive. This tends to happen with older publications and also some electronic sources. The following should help:
No author is given use [Anon.]
No date of publication is given use [n.d.]
No place of publication is given (sine loco) use [s.l.]
No publisher is given (sine nomine) use [s.n.]
Something other is not known use [n.k.]