Scelta delle aziende Siti usati: https://www.statista.com/statistics/247991/value-added-to-the-us-gdp-by-industry/
HealthCare Sito numero 1: https://www.valuepenguin.com/best-health-insurance-companies -> UnitedHealth Group Incorporated, Humana
Technology Sito numero 1: https://userguiding.com/blog/biggest-tech-companies/ -> Apple.Inc, Amazon
Real Estate Sito numero 1: https://propertyclub.nyc/article/biggest-real-estate-companies-in-usa -> RE/Max Sito numero 2: https://finance.yahoo.com/screener/predefined/ms_real_estate/?.tsrc=fin-srch -> Prologis, Inc.