1. CNN (2018, September 16). Hajj pilgrimage fast fact. Retrieved from https://www.cnn.com/2013/06/21/world/hajj-fast-facts/index.html
2. World Health Organization (WHO), (2018). Considerations for mass gathering events and Middle East respiratory syndrome coronavirus (MERS-CoV): Interim guidance. Retrieved from http://apps.who.int/iris/bitstream/handle/10665/272521/WHO-MERS-MG-15.1-Rev.1eng.pdf?sequence=1&isAllowed=y.
3. Ulmer, R. R., Sellnow, T. L., & Seeger, M. W. (2017). Effective crisis communication: Moving from crisis to opportunity. Thousand Oaks, CA: Sage Publications Inc.
4. Fearn-Banks, K. (2017). Crisis communications: A casebook approach (5th ed). Mahwah, N.J: Lawrence Erlbaum Associates.
5. Grunig, J., Grunig, L., & Dozier, D. (2006). The Excellence Theory. In Botan, C. & Hazelton, V. Public Relations Theory II (pp.171-198). Mahwah, NJ. Lawrence Erlbaum Associates, Inc.