Text this: Co<sub>0.85</sub>Bi<sub>0.15</sub>Fe<sub>1.9</sub>X<sub>0.1</sub>O<sub>4</sub> (X = Ce<sup>4+</sup>, Sm<sup>3+</sup>, Ho<sup>3+</sup>, and Er<sup>3+</sup>) Nanoparticles with Selective Anticancer Activity: A Structural and Morphological Approach
