Rule 10 specifies how to cite to cases and the federal section of Table T.1 specifies which reporter to cite to.
Sample citation for U.S. Supreme Court decision:
Roe v. Wade, 410 U.S. 113 (1973).
Sometimes you will see three parallel citations used as follows:
Roe v. Wade, 410 U.S. 113, 93 S. Ct. 705, 35 L. Ed. 2d 147 (1973).
However, the Bluebook mandates the use of only the U.S. Reports citation, if it is available. For recent cases for which the U.S. citation is not yet available, either the S. Ct. citation or the L. Ed. 2d citation, in that order, should be used.
Sample citation for federal Circuit Court of Appeals decision:
Robinson v. Shell Oil Co., 70 F.3d 325 (4th Cir. 1995).
Sample citation for federal district court decision:
Wolf v. J.I. Case Co., 617 F. Supp. 858 (E.D. Wis. 1985).