The ever-important treatise! Do you remember back in law school how your professors always told you to begin your research with secondary sources? We typically relied solely on the American Law Reports or Corpus Juris Secundum and went on our merry way. But there are so many more resources available for explaining and guiding the legal researcher along the path to knowledge. One of these is the treatise -- a publication that explains the deepest contents of an area of law and often includes forms, commentary, and case law and statutes of relevance as well as citations to other legal resources for more information.
Two sample treatises are Collier on Bankruptcy and Nimmer on Copyright. I'm studying bankruptcy this fall, and I know that Collier's treatise will be a great asset to understanding all of the terms and concepts within that particular field of law. These treatises are organized by a single editor who draws upon the legal knowledge and expertise of numerous co-authors. These multi-volume sets provide an authoritative, in-depth analysis of the area of law, which gives the researcher a firm foundation upon which to build their further research.