et. al., Gratia S. Sitorus ,. “Socio-Economic Life Cycle Assessment of Silangit Airport in Lake Toba Area”. Turkish Journal of Computer and Mathematics Education (TURCOMAT) 12, no. 8 (April 20, 2021): 3117–3124. Accessed May 7, 2024. https://turcomat.org/index.php/turkbilmat/article/view/4153.