Ancient literature of Bhutan is preserved in the National Library. The script used in Bhutanese literature is in the Bhutanese script (though evolved from Tibetan script) known as ''jo yig'' developed in the 16th century. The printing process of these books on handmade paper and its binding are display items at the National Library. Modern literature is still evolving and a religious biography of women titled ''delog'' is a popular religious work. There are many writers who write in English now, mostly short stories and collection of folk tales of Bhutan; a popular author is Kunzang Choeden.