元史
Trần Bình Trọng was killed afterwards in the same year at the age of 26. The death of Marquis Bảo Nghĩa was mourned by every member of Trần family and royal court, the Emperor posthumously entitled him as Prince Bảo Nghĩa (Bảo Nghĩa vương). The account of Battle of Đà Mạc and the capture of Trần Bình Trọng also appeared in the historical book of the Yuan Dynasty, the "History of Yuan". There was a difference between "Story of Annam" in "History of Yuan" and "Đại Việt sử kí toàn thư" about the date of the event at Đà Mạc, the Vietnamese work dated the battle in February while the exact day of the battle in the Chinese book was January 21 of Lunar calendar. According to modern historian Lê Mạnh Thát, the Chinese book might be more accurate in this case because most of the original historical records of the Trần Dynasty were destroyed by the Ming Dynasty during the fourth Chinese domination over Vietnam so maybe Ngô Sĩ Liên committed an error in copying this event.