1. Bartoszek, K., Guidotti, E., Iacus, S.M., Okrój, M.: Are official confirmed cases and fatalities counts good enough to study the covid-19 pandemic dynamics? A critical assessment through the case of Italy. Nonlinear Dyn. (2020). https://doi.org/10.1007/s11071-020-05761-w
2. Csáji, B.C., Browet, A., Traag, V.A., Delvenne, J.-C., Huens, E., Van Dooren, P., Smoreda, Z., Blondel, V.D.: Exploring the mobility of mobile phone users. Physica A 392(6), 1459–1473 (2013)
3. EDPB: Guidelines 04/2020 on the use of location data and contact tracing tools in the context of the covid-19 outbreak. https://edpb.europa.eu/our-work-tools/our-documents/linee-guida/guidelines-042020-use-location-data-and-contact-tracing_en (04/2020)
4. ENE. Estudio ene-covid19: Primera ronda estudio nacional de sero-epidemiologÍa de la infecciÓn por sars-cov-2 en espa$$\tilde{{{\rm N}}}$$a. Available at https://www.mscbs.gob.es/ciudadanos/ene-covid/docs/ESTUDIO_ENE-COVID19_PRIMERA_RONDA_INFORME_PRELIMINAR.pdf (2020)
5. European Commission: Commission recommendation (eu) on a common union toolbox for the use of technology and data to combat and exit from the covid-19 crisis, in particular concerning mobile applications and the use of anonymised mobility data, 2020/518. http://data.europa.eu/eli/reco/2020/518/oj (2020a)