sentences:  While the quốc ngữ script was created in the 17th century, it did not become popular outside of missionary groups until the early 20th century, when the French colonial administration mandated its use in French Indochina.By the mid-20th century, virtually all Vietnamese works of literature were composed in "quốc ngữ".Some defining works of literature include "The Tale of Kieu" by Nguyễn Du, and "Lục Vân Tiên" by Nguyễn Đình Chiểu.