Lepik, Madis. “ANALYZING THE USE OF TEXTBOOK IN MATHEMATICS EDUCATION: THE CASE OF ESTONIA”. Acta Paedagogica Vilnensia 350 (December 28, 2015): 90-102. Accessed November 27, 2021. https://www.journals.vu.lt/acta-paedagogica-vilnensia/article/view/9193.