Secondary sources are materials that define, discuss, explain,analyse and critique the law. They discuss the law, but are not the law itself.
Secondary sources such as Journals, Encyclopaedias, Dictionaries and Commentaries are a great place to start your legal research. Unlike primary sources (legislation, regulations, case law), secondary sources will help you learn about an area of law, and provide you with citations to relevant primary materials.
Law Library Basics: Legal Research - Secondary Sources NYU Law, 12 Sep 2022