《资治通鉴·隋纪·隋纪五》
平原郡东有豆子，背靠海且环绕着河，地形深远险阻，自从北齐的高氏王朝以来，成群的盗贼多隐匿在其中。
平原东有豆子，负海带河，地形深阻。自高齐以来，群盗多匿其中。
Douzi, east of Pingyuan County, backed by the sea and surrounded by rivers, the terrain is deep and perilous, since the Gao Dynasty of Northern Qi, hordes of bandits have often lurked in it.