Ebrey & Walthall 2014Lỗi harv: không có mục tiêu: CITEREFEbreyWalthall2014 (trợ giúp), [1], tr. 171, tại Google Books: Liao forces invaded Goryeo territory in 993. Instead of pushing for total victory, the Khitans negotiated a peace that forced Goryeo to adopt the Liao calendar and end tributary relations with Song (a violation of King Taejo's testamentary injunction never to make peace with the Khitan)."
Crossley, Pamela Kyle (2016). "Bohai/Parhae Identity and the Coherence of Dan gur under the Kitan/Liao Empire". International Journal of Korean History. Quyển 21 số 1. tr. 11-44. doi:10.22372/ijkh.2016.21.1.11.