In addition to the four treatises, you can access insights, pointers, guidance, strategies, tips, and commentary from B.E. Witkin and the Witkin Legal Institute.

Summary of California Law, 10th—States and examines every major substantive subject of statutory and common law.
California Civil Procedure, 4th—Discusses substantive and procedural subjects concerning attorneys, courts, jurisdictions, pleading, trial, appeal, and others.
California Criminal Law, 3rd—Substantive and procedural aspects, from arrest through post-conviction review.
California Evidence, 4th—Laws of evidence and evidence production and presentation in civil and criminal practice.