Chien-yi [Qian Yi; ca. 1032-1113 A.D.] - Qian specialized
in treatment of children and wrote the famous book Xiaoer Yaozheng
Zhijue (Key to Therapeutics of Children's Diseases). This book
presented the prescription Rehmannia
Six Formula (Liuwei Dihuang Wan), which has become the most
widely used yin-nourishing prescription, especially given to the
elderly despite its origins as a pediatric formulation.