↑ Ledyard, Gari K. The Korean Language Reform of 1446. Seoul: Shingu munhwasa, 1998.; Ledyard, Gari. «The International Linguistic Background of the Correct Sounds for the Instruction of the People.» In Young-Key Kim-Renaud, ed. The Korean Alphabet: Its History and Structure. Honolulu: University of Hawai’i Press, 1997.