KoshlyakovV. N., MitropolskiyY. A., SamoilenkoA. M., and UrbanskyV. M. “Oleksii Mykolajovych Boholyubov (on His 90th Birthday)”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 53, no. 3, Mar. 2001, pp. 294-5, https://umj.imath.kiev.ua/index.php/umj/article/view/4251.