Chinese medicine employs complex mixtures of remedies and does not appreciate the advantage or effectiveness of a single drug entity. Chinese herbal remedies are derived from animal, mineral, as well as arboreous and herbaceous sources. At least 1,500 different herbal drugs have been tested, analysed, and used in Chinese medicine; this is well documented in more than 50 different or revised editions of Pen-ts'ao. Both Sheng-nung Pen-ts'ao Ching, the earliest Chinese materia medica book, and the latest Pen-ts'ao Kang-mu are well-known and valuable compendia of herbal drugs.