The first type of source is oral history, but he calls this "the most problematic methodology in researching the incident" due in part to large discrepancies between the testimony of Japanese and Chinese eyewitnesses.
第一种来源是口述历史，但他称其是“研究这一事件最成问题的方法”，这部分归因于中国和日本目击者证词之间的巨大差异。