BanakhT. O., and VovkM. I. “Separately $Fσ$-Measurable Functions Are Close to Functions of the First Baire Class”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 56, no. 4, Apr. 2004, pp. 573–576, https://umj.imath.kiev.ua/index.php/umj/article/view/3778.