S. X. Sun and Q. Wang, A Comparison of Air Pollution in Developed and Developing Cities: A Case Study of London and Beijing. journal = {International Journal of Energy and Environmental Engineering}, [online]. World Academy of Science, Engineering and Technology. May 2022, vol. 185(5). 82 - 86 [viewed 29 March 2024]. Available from: https://publications.waset.org/pdf/10012540.