https://ppf.ucsf.edu/sites/ppf.ucsf.edu/files/webform/complete-list-of-official-united-airlines-contact-numbers-in-the-usa-full-detailed-guide.pdf https://ppf.ucsf.edu/sites/ppf.ucsf.edu/files/webform/complete-list-of-official-delta-airlines-contact-numbers-in-the-usa-full-detailed-guide_0.pdf https://ppf.ucsf.edu/sites/ppf.ucsf.edu/files/webform/complete-list-of-official-american-airlines-contact-numbers-in-the-usa-full-detailed-guide.pdf