Oliveira, Luanda Mara da Silva, et al. “Prevalence of Anti-SARS-CoV-2 Antibodies in Outpatients of a Large Public University Hospital in Sao Paulo, Brazil”. Revista Do Instituto De Medicina Tropical De São Paulo, vol. 62, Nov. 2020, p. e91, https://revistas.usp.br/rimtsp/article/view/183327.