For more straightforward and current summaries of a particular area of law, students and attorneys turn to hornbooks. The prevalence of the casebook method in American law schools has given rise to a market for commercial study aids "keyed" to a particular casebook edition. These study aids are generally summaries ("briefs") of the cases from the casebook to which it is "keyed," presenting them in the same order as the casebook. Often written by the same author who wrote the associated casebook, and published by the same company, "keyed" study aids are useful in distilling cases down to black-letter law. Popular study aid product lines include Legalines, High Court Case Summaries, and Gilbert Law Summaries published by West Thomson Reuters, Casenotes Legal Briefs by Aspen, and the Understanding series and Q&A series by LexisNexis. See also Sourcebook – similar structure used in the social sciences and humanities References Glanville Williams. "Case Books". Learning the Law. Eleventh Edition. Stevens and Sons. London. 1982. Pages 52 and 53. Sir Frederick Pollock. Oxford Lectures and other discourses. Macmillan and Co. London. 1890. Pages 105 and 106. Legal research Legal literature Legal education