About “Yongbiŏch'ŏn'ga”
Yongbiŏch'ŏn'ga was the first work written in Hangul. The book was published in 1447 and written by Chŏng Inji, An Chi and Kwŏn Chae. Its preface was written by Sŏng Sammun and Pak P'aengnyŏn. (Summary adapted from Wikipedia, CC BY-SA 4.0.)