Analysis of information sources in references of the Wikipedia article "A Tế Cách" in Vietnamese language version.
Quyển 45: 二十二年八月二十三日条:上曰:"八王则不欲留北京云,然耶?"(李)䅘曰:"八王言于九王曰:‘初得辽东,不行杀戮,故清人多为辽民所杀,今宜乘此兵威,大肆屠戮,留置诸王,以镇燕都,而大兵则或还守沈阳,或退保山海,可无后患。’九王以为:"先皇帝尝言,若得北京,当即徙都,以图进取。况今人心未定,不可弃而东还。’两王论议不合,因有嫌隙云。"