1. Premiere Pain Centers, New Brunswick, NJ, USA
2. West Virginia School of Medicine, Morgantown, WV 26506, USA
3. Stanford University School of Medicine, Palo Alto, CA 94304, USA
4. Johns Hopkins School of Medicine, Baltimore, MD 21205, USA
5. Mount Sinai School of Medicine, New York, NY 10029, USA
6. Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA