Ferdous, M. N., M. A. Islam, P. Chakrabortty, and S. Kabir. “Covid-19 Lockdown and Changes of Air Quality in the Most Polluted City of Bangladesh”. Journal of Scientific Research, vol. 13, no. 3, Sept. 2021, pp. 707-14, doi:10.3329/jsr.v13i3.50647.