Most of these are on reserve, ask for them at the Circulation Desk. Older versions may be in the stacks and can be checked out for longer periods of time.
Hornbook = single-volume scholarly work on a specific area of law geared towards law students. Hornbooks are very often condensed versions of longer works, called treatises.
Treatise = scholarly work, often multi-volume and with the author's name in the title (e.g., Corbin on Contracts). These offer in-depth analysis of an area of law, and include historical information and current trends.
Nutshell = short, single-volume, pocket-sized overview of an area of law, published by Thomson/West.