1. Kamps BS . Epidemiology. In: Kamps BS , Hoffmann C , eds. COVID reference. Germany: Steinhäuser Verlag, 2020: 31–52.
2. Cereda D , Tirani M , Rovida F . The early phase of the COVID-19 outbreak in Lombardy, Italy, 2020. Available: https://arxiv.org/abs/2003.09320 [Accessed 13 Apr 2020].
3. Red Nacional de Vigilancia Epidemiológica . Informe num. 22. Situación de COVID-19 en España a 13 de abril de 2020, 2020. Available: https://www.isciii.es/QueHacemos/Servicios/VigilanciaSaludPublicaRENAVE/EnfermedadesTransmisibles/Documents/INFORMES/Informes%20COVID-19/Informe%20n°%2022.%20Situación%20de%20COVID-19%20en%20España%20a%2013%20de%20abril%20de%202020.pdf [Accessed 13 Apr 2020].
4. Folgueira MD , Muñoz-Ruiperez C , Alonso-Lopez MA , et al . SARS-CoV-2 infection in health care workers in a large public hospital in Madrid, Spain, during March 2020. Available: https://www.medrxiv.org/content/ [Accessed 11 Apr 2020].
5. New York Times . ‘Here We Go Again’: A Second Virus Wave Grips Spain, 2020. Available: https://www.nytimes.com/2020/08/31/world/europe/coronavirus-covid-spain-second-wave.html