Wulandari, E. and Ayda, E. 2021. Analysis of Open-Ended Based Mathematics Learning Tools Oriented to Higher Order Thinking Skills Viewed from the Aspect of Validity. Edumatica : Jurnal Pendidikan Matematika. 11, 3 (Dec. 2021), 32–39. DOI:https://doi.org/10.22437/edumatica.v11i03.14404.