VanT.T.T., AlghamdiA.M. and AlkinaniA.A. 2024. On semiperfect $a$-rings. Ukrains’kyi Matematychnyi Zhurnal. 76, 6 (Jul. 2024), 907–914. DOI:https://doi.org/10.3842/umzh.v76i5.7491.