Challenges and Recommendations for Placebo Controls in Randomized Trials in Physical and Rehabilitation Medicine: A Report of the International Placebo Symposium Working Group - Fregni, Felipe; Imamura, Marta; Chien, Hsin Fen; Lew, Henry L.; Boggio, Paulo; Kaptchuk, Ted J.; Riberto, Marcelo; Hsing, Wu Tu; Battistella, Linamara Rizzo; Furlan, Andre (American Journal of Physical Medicine & Rehabilitation, 2010)