Susanti, Yuni, Takenobu Tokunaga, Hitoshi Nishikawa, and Hiroyuki Obari. “Controlling Item Difficulty for Automatic Vocabulary Question Generation”. Research and Practice in Technology Enhanced Learning 12 (December 19, 2017). Accessed May 18, 2024. https://rptel.apsce.net/index.php/RPTEL/article/view/2017-12025.