Hoang Thi Hien, and Bui Ha Trung. “FABRICATION AND RESEARCH OF CHARACTERISTICS OF NIO/PPY HYBRID FILMS USED FOR NH3 GAS SENSOR AT ROOM TEMPERATURE”. UTEHY Journal of Applied Science and Technology, Vol. 31, Mar. 2022, pp. 14-20, http://tapchi.utehy.edu.vn/index.php/jst/article/view/471.