《资治通鉴·宋纪·宋纪四》
北燕凡城守将封羽，举献城池投降，北魏军裹胁凡城三千多家百姓班师。
燕守将封羽以凡城降，收其三千馀家而还。
Feng Yu, the defending general of the Beiyan (Northern Yan) town of Fancheng, offered to surrender the city and the people of Fancheng. The Beiwei (Northern Wei) army took more than 3,000 households of the people of Fancheng and returned to their own territory.