wanra . Tarigan, T. Thamrin, L. Sembiring, H. . Silalahi, and I. Sembiring, “MAPPING PATTERNS OF THE SPREAD OF COVID-19 IN MEDAN CITY IN EFFORTS TO IMPROVE HEALTH SERVICE ACTIONS TO COMMUNITIES EXPOSED TO THE COVID-19 VIRUS USING THE APRIORI ALGORITHM METHOD”, Mantik, vol. 5, no. 2, pp. 1294-1304, Aug. 2021.