1. T. Acter, N. Uddin, J. Das, A. Akhter, "Since January 2020 Elsevier has created a Covid-19 resource centre with free information in English and Mandarin on the novel coronavirus Covid- 19 . The Covid-19 resource centre is hosted on Elsevier Connect , the company ' s public news and information," Science of the Total Environment Journal, vol. N/V, no. January, pp. 2-15, 2020.
2. Coronavirus disease (COVID-19) (no date) Who.int. Available at: https://www.who.int/health-topics/coronavirus (Accessed: June 20, 2021).
3. W.J. Guan, W.H. Liang, J.X. He, N.S. Zhong, "Cardiovascular comorbidity and its impact on patients with COVID-19," European Respiratory Journal, vol. 55, no. 6, pp. 1069-1076, 2020, doi:10.1183/13993003.01227-2020.
4. M.J. Hasan, A.M. Anam, S.M.R. Huq, R. Rabbani, "Impact of Comorbidities on Clinical Outcome of Patients with COVID-19: Evidence from a Single-center in Bangladesh," Health Scope, vol. 10, no. 1, pp. 1-9, 2021, doi:10.5812/jhealthscope.109268.
5. H. Ejaz, A. Alsrhani, A. Zafar, H. Javed, K. Junaid, A.E. Abdalla, K.O.A. Abosalif, Z. Ahmed, S. Younas, "COVID-19 and comorbidities: Deleterious impact on infected patients," Journal of Infection and Public Health, vol. 13, no. 12, pp. 1833-1839, 2020, doi:10.1016/j.jiph.2020.07.014.