Electroacupuncture for tapering off long-term benzodiazepine use: study protocol of randomized controlled trial oleh Wing-Fai Yeung, Ka-Fai Chung, Zhang-Jin Zhang, Wai-Chi Chan, Shi-Ping Zhang, Roger Man-Kin Ng, Connie Lai-Wah Chan, Lai-Ming Ho, Yee-Man Yu, Li-Xing Lao