- https://www.cde.state.co.us/sites/default/files/webform/easy-how-do-I-check-in%20online-for-united-airlines.pdf
- https://www.cde.state.co.us/sites/default/files/webform/online-how-do-I-check-in%20online-for-united-airlines.pdf
- https://www.cde.state.co.us/sites/default/files/webform/here-how-do-I-check-in%20online-for-united-airlines.pdf
- https://www.cde.state.co.us/sites/default/files/webform/checked-how-do-I-check-in%20online-for-united-airlines.pdf
- https://www.cde.state.co.us/sites/default/files/webform/info-how-do-I-check-in%20online-for-united-airlines.pdf
- https://www.cde.state.co.us/sites/default/files/webform/team-how-do-I-check-in%20online-for-united-airlines.pdf
- https://www.cde.state.co.us/sites/default/files/webform/call-how-do-I-check-in%20online-for-united-airlines.pdf
- https://www.cde.state.co.us/sites/default/files/webform/check-how-do-I-check-in%20online-for-united-airlines.pdf
- https://www.cde.state.co.us/sites/default/files/webform/best-united-airlines-check-in.pdf
- https://www.cde.state.co.us/sites/default/files/webform/verifying-united-airlines-check-in.pdf
- https://youtu.be/bZmkCFSS1-Q
- https://youtu.be/5YFtmjeUPJU
- https://youtu.be/UXksBwehQEM
- https://youtu.be/BrSkq-2r8Go
- https://youtu.be/m7EN0dTUe4w
- https://youtu.be/ktiRGV9mk7I
- https://youtu.be/lVAQVzhie_0
- https://youtu.be/Sok3HyaPc7M
- https://youtu.be/vZTqrnMizMg
- https://youtu.be/OOnh9SZOvG8
- http://www.trailforums.com/t/how-to-check-in-on-frontier-airlines-everything-you-need-to-know-before-you-fly/58899
- http://www.trailforums.com/t/step-by-step-guide-how-do-i-check-in-on-frontier-airlines/58865
- http://www.trailforums.com/t/how-to-check-in-on-frontier-airlines-a-simple-step-by-step-guide-for-travelers/58884
- https://discourse.pro/t/topic/463
- https://discourse.pro/t/topic/464
- https://discourse.pro/t/topic/465
- https://discourse.pro/t/topic/466
- https://discourse.pro/t/topic/467
- https://discourse.pro/t/topic/468
- https://discourse.pro/t/topic/469
- https://discourse.pro/t/topic/470
- https://discourse.pro/t/topic/471
- https://discourse.pro/t/topic/472
- https://discourse.pro/t/topic/474
- https://discourse.pro/t/topic/475
- https://discourse.pro/t/topic/476
- https://discourse.pro/t/topic/477
- https://discourse.pro/t/topic/478
- https://discourse.pro/t/topic/479
- https://discourse.pro/t/topic/480