Secondary sources help the researcher to identify and understand the law.
Secondary sources are not law and are never cited as legal authority. They
include legal dictionaries and encyclopedias, journal articles, books, treatises, practice aids, self-help materials, and finding tools.
It is easier and generally more effective for a researcher to consult a secondary source to read about key statutes, regulations, and cases governing a particular area of law, e.g., family law, probate law, employment law, criminal law, before attempting to identify, locate and analyze those same resources using indexes for codes and regulations and digests for cases.