Facci, L. M., J. P. Nowotny, F. Tormem, and V. F. M. Trevisani. “Effects of Transcutaneous Electrical Nerve Stimulation (TENS) and Interferential Currents (IFC) in Patients With Nonspecific Chronic Low Back Pain: Randomized Clinical Trial”. São Paulo Medical Journal, vol. 129, no. 4, July 2011, pp. 206-1, https://periodicosapm.emnuvens.com.br/spmj/article/view/1608.