Tai-Jin Kim. “Vaccine, Emergence, Termination, Sunspot Number As ON-OFF Switch for COVID-19 Pandemic With 25 Worst-Hit Countries”. Global Journal of Medical Research, vol. 20, no. K11, Oct. 2020, pp. 17-41, https://medicalresearchjournal.org/index.php/GJMR/article/view/2228.