https://collaboratory.gse.upenn.edu/sites/default/files/webform/List-of-Trip-com-Customer-Service-USA-Contact-Number-All-in-one%20guide.pdf https://collaboratory.gse.upenn.edu/sites/default/files/webform/Complete-List-Of-Hyatt-RESERVATIONS-By-Us-Contact-Numbers-A%20Step-by-step-Guide.pdf https://collaboratory.gse.upenn.edu/sites/default/files/webform/Complete-List-Of-Marriott-RESERVATIONS-By-Us-Contact-Numbers-A%20Step-by-step-Guide.pdf https://collaboratory.gse.upenn.edu/sites/default/files/webform/Complete-List-Of-IHG%20hotel-RESERVATIONS-By-Us-Contact-Numbers-A%20Step-by-step-Guide.pdf