1. Adie Tomer, and Joseph W. Kane. 2020. How to Protect Essential Workers During COVID-19. Brookings Institution. https://www.brookings.edu/research/how-to-protect-essential-workers-during-covid-19/#footref-1. Accessed 9 Mar 2021.
2. Blau, Francine D., Josefine Koebe, and Pamela A. Meyerhofer. 2020. Essential and Frontline Workers in the COVID-19 Crisis. Econofact. https://econofact.org/essential-and-frontline-workers-in-the-covid-19-crisis. Accessed 24 Aug 2020.
3. Center for Disease Control and Prevention. 2021. Interim List of Categories of Essential Workers Mapped to Standardized Industry Codes and Titles. www.cdc.gov/vaccines/covid-19/categories-essential-workers.html. Accessed 11 May 2021.
4. Department of Homeland Security. 2020. Guidance on the Essential Critical Infrastructure Workforce: Ensuring Community and National Resilience in COVID-19 Response, Version 2.0. https://www.cisa.gov/sites/default/files/publications/CISA_Guidance_on_the_Essential_Critical_Infrastructure_Workforce_Version_2.0_1.pdf. Accessed 3 Mar 2021.
5. Department of Homeland Security. 2020. Guidance on the Essential Critical Infrastructure Workforce: Ensuring Community and National Resilience in COVID-19 Response, Version 4.0. https://www.cisa.gov/sites/default/files/publications/ECIW_4.0_Guidance_on_Essential_Critical_Infrastructure_Workers_Final3_508_0.pdf. Accessed 3 Marc 2021.