Firdaus M, Wahab Z, Widiyanti M, Shihab MS. Effect of price and promotion on customer loyalty of domestic and export coal in the time of the COVID-19 pandemic. ijss [Internet]. 2022Jan.8 [cited 2024Jul.16];5(1):8-14. Available from: https://sloap.org/journal/index.php/ijss/article/view/1820