A treatise is an extended, usually exhaustive book on a subject. You may consult treatises at any stage in your research.
Torts. Epstein, Richard Allen (Print).
The Torts Process. Henderson, James A., et al. (Print).
Torts: The Civil Law of Reparation for Harm Done by Wrongful Act. Little, Joseph W., et.al. (Print).
The Law of Torts. Osborne, Philip (Print).
The Law of Torts: Examples and Explanations. Glannon, Joseph (Print).
California Civil Practice - Torts (Westlaw).
California Torts (Lexis).