Sharan A, Groff MW, Dailey AT, Ghogawala Z, Resnick DK, Watters WC, Mummaneni PV, Choudhri TF, Eck JC, Wang JC, Dhall SS, Kaiser MG. Guideline update for the performance of fusion procedures for degenerative disease of the lumbar spine. Part 15: electrophysiological monitoring and lumbar fusion. J Neurosurg Spine. 2014 Jul; 21(1):102-5.