삼국유사
In some editions of Samguk Yusa, one of the oldest surviving Korean history books, the name Hwanin (桓因), the mythical grandfather of Gojoseon's founder Dangun, appears as if it is instead written "Hwanguk" (桓國), which would mean "The Hwan nation." Some people argue that this is an evidence that the original manuscript of Samguk Yusa wrote "Hwanguk" instead of "Hwanin."