Bogolyubov, A. N. “Jubilees Iosyp Zakharovych Shtokalo (on the 100th Anniversary of His Birth)”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 50, no. 8, Aug. 1998, pp. 1152–1153, https://umj.imath.kiev.ua/index.php/umj/article/view/4866.