https://support.google.com/edu/classroom/thread/334239358?hl=en&sjid=12629586493330029268-NA

https://intercom.help/all-airlines-support/en/articles/10980813-weekly-flight-what-day-of-the-week-are-frontier-flights-cheapest

https://intercom.help/all-airlines-support/en/articles/10979767-am-faq-prices-how-to-change-your-flight-with-aeromexico

https://intercom.help/all-airlines-support/en/articles/10980143-%E1%B4%80%CA%99%E1%B4%8F%E1%B4%9C%E1%B4%9B-%E1%B4%84%E1%B4%8F%C9%B4%E1%B4%9B%E1%B4%80%E1%B4%84%E1%B4%9B%C9%AA%C9%B4%C9%A2-%E1%B4%9C%EA%9C%B1%E1%B4%80-how-do-i-contact-united-airlines-customer-service

https://intercom.help/all-airlines-support/en/articles/10980691-what-is-the-best-way-to-complain-to-expedia-assistant-help

https://intercom.help/all-airlines-support/en/articles/10980922-absolutely-yes-what-is-the-24-hour-rule-in-klm

https://www.quecochemecompro.com/opiniones/sky-telefono-peru-como-puedo-comunicarme-con-sky-airlines-peru-2/

https://intercom.help/all-airlines-support/en/articles/10980136-get-in-touch-fast-how-do-i-contact-united-airlines-customer-service

https://intercom.help/all-airlines-support/en/articles/10980909-how-do-i-complain-to-expedia