Nguyen, L. P., B. V. Tuong, N. H. Thu, N. Sura, and L. N. Thuy. “Nickel Recovery from Spent Catalyst for Environmental Catalyst Preparation: The Influence of Pre-Treatment Conditions and Ni Loading on Removal of Carbon Monoxide over N Ni/γ-Al2O3 Catalysts”. Petrovietnam Journal, Vol. 1, Jan. 2015, pp. 42-51, https://tapchidaukhi.vn/index.php/TCDK/article/view/435.