Nguyen, Hien, 		Le, Qui, 		Ngo, Dai, 		Nguyen, Hanh, 		Huynh, Chinh, AND 		Dao, Lin.
" Preparation and investigation of optical properties of ZnO: Co powders" <em>VNU Journal of Science: Mathematics - Physics</em> [Online], Volume 20 Number 3AP (26 April 2017)