KoshlyakovV. N., MitropolskiyYu. A., SamoilenkoA. M., and UrbanskyV. M. 2001. “Oleksii Mykolajovych Boholyubov (on His 90th Birthday)”. Ukrains’kyi Matematychnyi Zhurnal 53 (3), 294-95. https://umj.imath.kiev.ua/index.php/umj/article/view/4251.