《宋书·志·卷十一》
左史修记言之史，右史修记事之史，记事之史的典型是《春秋》，记言之史则以《尚书》为代表。
志序历上左史记言，右史记事，事则《春秋》是也，言则《尚书》是也。
The Left Historian recorded the words spoken in the court, while the Right Historian recorded the events that happened. The typical work of recording events was the Spring and Autumn Annals, while the typical work of recording words spoken in the court was the Shangshu.