GOGA, Firuţa, et al. “INFLUENCE OF THE THERMAL TREATMENT ON THE COLOUR OF RO٠Al₂O₃ (R=Co, Ni) TYPE SPINEL PIGMENTS PREPARED BY A MODIFIED SOL – GEL METHOD”. Studia Universitatis Babeș-Bolyai Chemia, vol. 61, no. 3, Sept. 2016, pp. 263-7, https://studia.reviste.ubbcluj.ro/index.php/chemia/article/view/8349.