Yusuf, Slamet. P. H., Thomas Sukardi , Mohd. Khairudin. 2020. “Learning Model Higher Order Thinking Skills at Vocational High School: Achievement and Thinking Behavior”. International Journal of Advanced Science and Technology 29 (7s), 158 -70. https://sersc.org/journals/index.php/IJAST/article/view/9424.