Sičiūnienė Viktorija, and Dargytė Janina. “Learning Geometry in Pro-Gymnasium: Achievements and Challenges”. Lietuvos matematikos rinkinys 53, no. B (December 20, 2012): 231–236. Accessed December 9, 2021. https://www.journals.vu.lt/LMR/article/view/17133.