The imperial court of the Song dynasty placed great importance on medicine. Even scholar-officials were engaged in compiling medical books. Hong Zun (1120−74), in his spare time after his working hours, sought and collected medical prescriptions and compiled this work, entitled Hong shi ji yan fang (Hong's collection of effective prescriptions). It contains 167 prescriptions, which were collected from his many years of research and which proved to be practical and effective. The work was engraved in the sixth year of the Qiandao reign (1170) and was printed on document paper dated 1180−81. The practice of printing texts on document paper, originally intended for official documents, was a unique feature in the history of Chinese printing. This printed book using official document paper probably is the earliest extant example; it is thus of great historical value, even though it was not widely circulated.