《容斋随笔·卷十六·三长月》
《北宋书》称高洋密谋篡夺东魏政权，他的大臣宋景业说： 应该在仲夏五月接受禅让。 
《北齐书》云高洋谋篡魏，其臣宋景业言： 宜以仲夏受禅。 
"Book of Northern Song" states that Gao Yang secretly plotted to usurp the power of Eastern Wei, and his minister Song Jingye said: "We should accept the surrender in midsummer May."