Jamil, M. S., Mohamad Japeri, A. Z. U.-S., Abu Bakar, A. A., Muhammad Ali, K. A., & Ahmat, H. (2019). Identification of Source Contributions to Air Pollution in Penang Using Factor Analysis. International Journal of Integrated Engineering, 11(8), 221–228. Retrieved from https://publisher.uthm.edu.my/ojs/index.php/ijie/article/view/2472