Imbelloni, L. E., M. A. Gouveia, and J. A. Cordeiro. “Continuous Spinal Anesthesia Versus Combined Spinal Epidural Block for Major Orthopedic Surgery: Prospective Randomized Study”. São Paulo Medical Journal, vol. 127, no. 1, Jan. 2009, pp. 7-11, https://periodicosapm.emnuvens.com.br/spmj/article/view/1839.