https://www.wyomilitary.wyo.gov/wp-content/uploads/formidable/14/e-x-p-e-dia-usa-customer-service-full-step-by-step-guide.pdf
https://education.aaaai.org/sites/default/files/webform/complete-list-of-official-expedia-customer-contact-numbers-in-the-usa-the-ultimate-detailed-guide.pdf
https://id.one-line.com/sites/g/files/lnzjqr1601/files/2025-08/United-Airlines-2025-Full-Customer-Contact-Numbers-in-the-USA.pdf
https://educativ.net/forums/topic/39654-bookingcom%C2%AE%EF%B8%8F-customer-service%E2%84%A2%EF%B8%8F-usa-contact-numbers-a-ultimate-complete-guide%C2%AE%EF%B8%8F/
https://educativ.net/forums/topic/39686-%E2%98%857%E2%98%85-ways-to-speak-with-westjet-airlines%C2%AE%EF%B8%8F-live-agent-%E2%80%93-detailed-guide/
https://discuss.tindie.com/t/complete-guide-of-british-airways-usa-contact-numbers-a-2025-step-by-step-guide/533987
https://officialcustomerservicehelpdesk.zohodesk.com/portal/en/kb/articles/faq-what-is-the-cheapest-day-of-the-week-to-book-a-flight-on-delta
https://educativ.net/forums/topic/39653-complete-list-of-official-delta-airlines%C2%AE-customer%C2%AE-contact-numbers-in-usa-an-updated-guide/