MotornayaO. V., MotornyiV. P., and SedunovaV. V. “On the Classification of Functions Integrable on a Segment”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 68, no. 5, May 2016, pp. 642-56, https://umj.imath.kiev.ua/index.php/umj/article/view/1868.