While you will most often cite to cases in reporters, only a small percentage of cases are actually designated for publication by a court and published in a reporter. Many cases are unpublished, but still available in databases, such as Westlaw, Lexis, Bloomberg Law, or elsewhere. Rule 10.8.1 describes how to cite an unpublished case and there are examples in the chart at the beginning of Rule 10 (p. 95).
A citation to an unpublished case that is available in Westlaw, Lexis, Bloomberg Law, or another "widely used electronic database" (Rule 10.8.1(a)) has the following five elements:
Here is an example:
United States v. Bennett, No. 05-CR-6050 CJS, 2005 WL 2709572 (W.D.N.Y. Oct. 21, 2005)
If an unpublished case is not available in an electronic database and only available as a slip opinion, the citation is the same, except without the database identifier:
United States v. Bennett, No. 05-CR-6050 CJS (W.D.N.Y. Oct. 21, 2005)
For how to cite specific pages in unpublished opinions, see Rule 10.8.1(a) and 10.8.1(b).