https://regions-and-cities.europa.eu/sites/default/files/webform/multimedia_center/_sid_/UnitedMexicoTelefonoComollamaraUnitedAirlinesdesdeMexico.pdf

https://regions-and-cities.europa.eu/sites/default/files/webform/multimedia_center/_sid_/United%20Mexico%20Telefono%20%C2%BFComo%20llamar%20a%20United%20Airlines%20desde%20Mexico.pdf