https://www.transfermarkt.com/-flight-check-in-does-united-require-24-hour-check-in-/thread/forum/659/thread_id/7896/page/1#anchor_7907
https://www.transfermarkt.com/-flight-check-in-does-united-require-24-hour-check-in-/thread/forum/659/thread_id/7896/page/1#anchor_7907
https://www.transfermarkt.com/-flight-check-in-does-united-require-24-hour-check-in-/thread/forum/659/thread_id/7896/page/1#anchor_7907