《资治通鉴·晋纪·晋纪二十》
他的弟弟杜郁劝说他去迎接苻健，他没有听从。杜郁便率领他的部队投降苻健。
洪弟郁劝洪迎健，洪不从；郁帅所部降于健。
His younger brother Du Yu advised him to submit to Fu Jian, but he wouldn't listen, so Du Yu took his troops to surrender to Fu Jian.