1. Otorhinolaryngology, Head and Neck Surgery , Golestan University of Medical Sciences , Gorgan , Iran
2. Medical Librarianship and Information Sciences, Research Center of Gastroenterology and Hepatology , Golestan University of Medical Sciences , Gorgan , Iran
3. Department of Biostatistics and Epidemiology, Faculty of Health , Health Management and Social Development Research Center, Golestan University of Medical Sciences , Gorgan , Iran