https://www.mmobugs.com/forums/index.php?threads/11-maneras-de-contactar-con-el-servicio-de-atenci%C3%B3n-al-cliente-de-american-airlines-por-tel%C3%A9fono-correo-electr%C3%B3nico-o-chat-gu%C3%ADa-completa-de-ayuda.36565/

https://offcial-american-airlines-help.feedbear.com/boards/general-feedback/posts/12-ways-to-dial-how-do-i-speak-to-someone-at-american-airlines-a-complete-guide

https://www.mmobugs.com/forums/index.php?threads/11-maneras-de-contactar-con-el-servicio-de-atenci%C3%B3n-al-cliente-de-latam-airlines-por-tel%C3%A9fono-correo-electr%C3%B3nico-o-chat-gu%C3%ADa-completa-de-ayuda.36562/

https://www.perio.org/wp-content/uploads/ninja-forms/40/07-ways-to-contact-expedia-customer-service-by-phone-number-email-and-chat-options.pdf

https://papers.ssrn.com/sol3/papers.cfm?abstract_id=5320706

https://www.historycouncilvic.org.au/allairlineshelphub/12_ways_to_contact_to_someone_at_austrian_airlines_customer_service_a_complete_guide

https://www.perio.org/wp-content/uploads/ninja-forms/40/09-instant-ways-to-get-in-touch-with-quickbooks-payroll-us-support-a-complete-user-guide.pdf

https://www.mmobugs.com/forums/index.php?threads/11-maneras-de-contactar-con-el-servicio-de-atenci%C3%B3n-al-cliente-de-latam-airlines-por-tel%C3%A9fono-correo-electr%C3%B3nico-o-chat-gu%C3%ADa-completa-de-ayuda.36560/

https://aircanadahelpcenter.userjot.com/board/p/15-ways-to-contact-how-can-i-speak-to-someone-at-air-canada-customer-service-a-step-by-step-guide

https://perio.org/wp-content/uploads/ninja-forms/40/10-Ways-To-Speak-with-QuickBooks-US-Payroll-How-to-Connect-with-QuickBooks-Customer-Support-Guide.pdf