Legal encyclopedias provide a general summary of the law. Their footnotes include references to relevant cases, statutes, practice guides, and other resources. Legal encyclopedias typically don't include detailed procedural guidance or sample forms.
Legal encyclopedias usually aren't detailed enough to be the final destination on an attorney's research trial, but they are often a good first stop for a researcher working with an unfamiliar area of the law.
The Pennsylvania Law Encyclopedia (available on Lexis) discusses the basic elements of many subject areas pertinent to the practice of law in Pennsylvania. For each major issue discussed, the Pennsylvania Law Encyclopedia provides "black letter" law summaries that precede more in-depth analysis of case law, statutes, and rules.
Summary of Pennsylvania Jurisprudence 2d (available on Westlaw) provides concise text of civil and criminal substantive law, and discussion of relevant statutes, rules, regulations, and landmark and federal cases.