1. Department of Medicine, Section of Cardiovascular Medicine University of Oklahoma Health Sciences Center Oklahoma City Oklahoma USA
2. Department of Medicine, Section of Cardiovascular Medicine Allegheny General Hospital Pittsburgh Pennsylvania USA
3. Department of Medicine University of Oklahoma Health Sciences Center Oklahoma City Oklahoma USA
4. Robert M. Bird Health Sciences Library University of Oklahoma Health Sciences Center Oklahoma City Oklahoma USA
5. Department of Biostatistics and Epidemiology University of Oklahoma Health Sciences Center Oklahoma City Oklahoma USA
6. Division of Cardiovascular Medicine University of California Davis Sacramento California USA
7. Department of Cardiovascular Medicine Mayo Clinic Rochester Minnesota USA
8. University of Adelaide and Royal Adelaide Hospital Adelaide Australia