1. Thoracic Endoscopy and Pulmonology Unit; Maggiore Hospital; Bologna Italy
2. Pulmonary Diseases Unit; Ospedale Infermi; Rimini Italy
3. Biometry and Medical Statistics Unit; IRCCS Policlinico San Matteo Foundation; Pavia Italy
4. Scientific Documentation Service; IRCCS Policlinico San Matteo Foundation; Pavia Italy