Zhang Zhongjing is the most famous of China's ancient herbal doctors. He is known for his book, which was later divided into two parts: Shang Han Lun and Chin Kuei Yao Lueh [Jin Gui Yao Lue]. In particular, the section known as the Shang Han Lun became the fundamental text for all traditional herb prescribing. Not only did it contain over 100 effective formulas (many of them still used today), but the text implied a theoretical framework that led to hundreds of books analyzing, explaining, and reforming it. The other section is best known for some of the formulas, such as the gynecological remedy Tang-kuei and Peony Formula [Danggui Shaoyao San] which is today applied to infertility, disorders during pregnancy, prevention of miscarriage, and post-partum weakness. His work might have been lost had it not been for the efforts of Wang Shu-Ho .