Source: https://www.researchgate.net/publication/339730023_First_cases_of_coronavirus_disease_2019_COVID-19_in_the_WHO_European_Region_24_January_to_21_February_2020/fulltext/5e619d28458515163551fa1f/First-cases-of-coronavirus-disease-2019-COVID-19-in-the-WHO-European-Region-24-January-to-21-February-2020.pdf