Suhartini & Martyanti, A. (2017). Meningkatkan Kemampuan Berpikir Kritis pada Pembelajaran Geometri berbasis Etnomatematika. Jurnal Gantang, 2(2), hlm 105-111. [Online]. Diakses dari: https://ojs.umrah.ac.id/index.php/gantang/article/view/198
Usiskin, Z. (1982). Van Hiele Levels and Achievement in Secondary School Geometry (Final report of the Cognitive Development and Achievement in Secondary School Geometry Project) Chicago: University of Chicago. (ERIC Document Reproduction Service No. ED220288).