Mačys, Juozas Juvencijus, and Jurgis Sušinskas. “Propedeutics of Series in a School”. Lietuvos matematikos rinkinys 54, no. B (December 20, 2013): 146–150. Accessed June 17, 2024. https://www.journals.vu.lt/LMR/article/view/17181.