1. Department of Periodontology and Prosthodontics, G. Eastman Dental Hospital, Rome, Italy
2. Private practice, Rome, Italy
3. Division of Periodontics, Department of Advanced Oral Sciences and Therapeutics, School of Dentistry, University of Maryland, Baltimore, MD, USA
4. Department of Periodontology, International University of Catalonia, Barcelona, Spain
5. Private practice, San Juan, Puerto Rico
6. Health Sciences and Human Services Library, University of Maryland, Baltimore, Baltimore, MD, USA