F. M. Othman, A. A. Abdul-hamead, and N. M. Ali, “Fabrication and Characterization of Tri Metal Oxides by Chemical Spray Pyrolysis Technique as a Gas Sensor”, alkej, vol. 12, no. 4, pp. 132–140, Dec. 2017, doi: 10.22153/kej.2016.05.007.