BakanA. G., and HolubA. P. “On Sequences That Do Not Increase the Number of Real Roots of Polynomials”. Ukrains’kyi Matematychnyi Zhurnal, Vol. 45, no. 10, Oct. 1993, pp. 1323–1331, https://umj.imath.kiev.ua/index.php/umj/article/view/5937.