CHO, H. The Analysis on the Length and Content Changes on Secondary Mathematics Textbooks in North Korea. Journal of Mathematics Education at Teachers College, [S. l.], v. 1, n. 2, 2010. DOI: 10.7916/jmetc.v1i2.689. Disponível em: https://journals.library.columbia.edu/index.php/jmetc/article/view/689. Acesso em: 15 aug. 2022.