12Johns Hopkins CSSE. "Coronavirus COVID19 (2019-nCoV)"(ArcGIS). Coronavirus COVID-19 Global Cases. Diarsipkan dari versi aslinya tanggal March 4, 2020. Diakses tanggal March 19, 2020.
↑Higgins-Dunn, Noah; Miller, Hannah (2020-04-20). "Coronavirus antibody testing shows LA County outbreak is up to 55 times bigger than reported cases". CNBC (dalam bahasa Inggris). Diarsipkan dari versi aslinya tanggal April 21, 2020. Diakses tanggal 2020-04-21. USC and the health department released preliminary study results that found that an estimated 4.1% of the county's adult population has antibodies to the coronavirus, estimating that between 221,000 adults to 442,000 adults in the county have had the infection.