Role of buprenorphine in prolonging the duration of post-operative analgesia in percutaneous nephrolithotomy: Comparison between bupivacaine versus bupivacaine and buprenorphine co... oleh Jonnavithula Nirmala, Anil Kumar, Rahul Devraj, Sriramoju Vidyasagar, Gunta Ramachandraiah, Pisapati V. L. N. Murthy