1. www.mayoclinic.org/tests-procedures/bronchoscopy/about/pac-20384746
2. www.webmd.com/lung-cancer/qa/how-is-a-bronchoscopy-used-to-diagnose-lung-cancer
3. British Thoracic Society Bronchoscopy Guidelines Committee, a Subcommittee of the Standards of Care Committee of the British Thoracic Society. 'British Thoracic Society guidelines on diagnostic flexible bronchoscopy'. Superseded By 2013 Guideline: British Thoracic Society Guidelines on Diagnostic Flexible Bronchoscopy. Thorax 2001