Analysis of information sources in references of the Wikipedia article "二次安检 (美国)" in Chinese language version.
Southwest... clerk tore up the boarding pass, printed out another one with a checkerboard pattern on it... you become selected for secondary screening...（页面存档备份，存于互联网档案馆）
Southwest... clerk tore up the boarding pass, printed out another one with a checkerboard pattern on it... you become selected for secondary screening...（页面存档备份，存于互联网档案馆）
