1. Division of Gastroenterology and Hepatology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
2. Division of Gastroenterology and Hepatology, University of North Carolina, Chapel Hill, North Carolina, USA
3. University of Tennessee Health Science Center Library, Memphis, Tennessee, USA
4. University of Sao Paulo, Sao Paulo, Brazil
5. Humanitas University, Milan, Italy
6. Division of Gastroenterology and Hepatology, Johns Hopkins University, Baltimore, Maryland, USA