1. University of New Mexico; Albuquerque NM USA
2. Department of Epidemiology; Johns Hopkins Bloomberg School of Public Health; Baltimore Maryland USA
3. Rehabilitation Research Center; Department of Neurology; University of Maryland at Kernan Rehabilitation Hospital; Baltimore MD USA
4. Hirsh Health Sciences Library; Tufts University; Boston MA USA
5. Department of Epidemiology; JHU Bloomberg School of Public Health; Baltimore MD USA
6. School of Population and Public Health, Faculty of Medicine; University of British Columbia; Vancouver Canada
7. Division of General Internal Medicine; Johns Hopkins School of Medicine; Baltimore MD USA