https://archive.org/details/general-list-of-delta-airlinestm-contactr-numbers-in-the-usar-247-live-person-the-ultimate-detailed https://archive.org/details/official-complete-list-of-all-deltar-airlines-customertm-contact-numbers-in-the-usa-updated   https://archive.org/details/general-list-of-deltatm-contactr-numbers-in-the-usar