The Bluebook - Proper Federal Citation

The University of Pennsylvania provides the Bluebook online - you must pay for a membership to access.  Tips, however, are provided for free.  They are organized into five (5) areas (below) and with a bit of background knowledge, you may feel comfortable that you've found your answer after perusing the BlueTips archives for a bit:

What about Texas' Greenbook? 

Gotta buy it - it's offered by the Texas Law Review.