1. Human Engineering Research Laboratories, Veterans Affairs Pittsburgh Healthcare System, Pittsburgh, PA 15206, USA
2. School of Health and Rehabilitation Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
3. Department of Epidemiology, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, PA 15261, USA
4. Health Sciences Library, University of Pittsburgh, Pittsburgh, PA 15261, USA
5. Department of Prosthetics and Orthotics, School of Health and Rehabilitation Sciences, University of Pittsburgh, Pittsburgh, PA 15206, USA