1. Department of Biostatistics and Epidemiology, Hudson College of Public Health, University of Oklahoma Health Sciences Center , Oklahoma City, OK, USA
2. College of Medicine, University of Oklahoma Health Sciences Center , Oklahoma City, OK, USA
3. Robert M. Bird Health Sciences Library, University of Oklahoma Health Sciences Center , Oklahoma City, OK, USA
4. Department of Family and Preventive Medicine, College of Medicine, University of Oklahoma Health Sciences Center , Oklahoma City, OK, USA