1. S. Freishtat, Chicago Tribune, As travel rebounds, airlines offer perks like 10000$ signing bonus to draw new employees,https://www.chicagotribune.com/business/ct-biz-united-10k-bonus-airline-hiring-shortage-20220228- lxjvmyjxmrfzzcbfkk7vmhgfoy-story.html, 28th February 2022, latest accessed April 2023