Ang, Z. Y., N. Z. Balqis-Ali, J. Anis-Syakira, Y.-L. Kong, S. Md Sharif, and W. H. Fun. “COVID-19 Clusters in Malaysia: Characteristics, Detection Methods and Modes of Early Transmission”. Western Pacific Surveillance and Response, vol. 14, no. 4, Nov. 2023, p. 11, doi:10.5365/wpsar.2023.14.4.1058.