Khumkhong, Phiraya, Songchai Ugsornkid, and Tongta Somchaipeng. 2024. “Effects of Using Open Approach on Mathematical Problem-Solving Ability of Arithmetic Series of 11th Grade Students”. Interdisciplinary Academic and Research Journal 4 (5). Maha Sara Kham, TH.:437-52. https://doi.org/10.60027/iarj.2024.278069.