Firdaus, Muhammad, Zakaria Wahab, Marlina Widiyanti, and Muchsin Saggaf Shihab. 2022. “Effect of Price and Promotion on Customer Loyalty of Domestic and Export Coal in the Time of the COVID-19 Pandemic”. International Journal of Social Sciences 5 (1):8-14. https://doi.org/10.21744/ijss.v5n1.1820.