https://forum.elecrow.com/discussion/26451/a-quick-list-of-official-delta-airlines-%EF%B8%8F-%EF%B8%8Fcustomer-usa-contact-number/p1?new=1
https://forum.priceplow.com/t/complete-list-of-official-united-airlines-customer-care-contact-numbers-in-the-usa-full-detailed-guide/16301
https://forum.priceplow.com/t/full-list-united-airlines-customer-service-number-usa-contact-numbers-guide-2025/16307