Szymańska, E., and Z. Bońkowska. “Children with Down`s syndrome motor disturbance at age of 0 to 3-own cases analysis taking additional factors burdening the development into consideretion”. European Journal of Clinical and Experimental Medicine, vol. 3, no. 1, Mar. 2005, pp. 58–62, https://journals.ur.edu.pl/ejcem/article/view/13487.