A pilot study of the efficacy of heart rate variability (HRV) biofeedback in patients with fibromyalgia - Hassett, AL; Radvanski, DC; Vaschillo, EG; Vaschillo, B; Sigal, LH; Karavidas, MK; Buyske, S; Lehrer, PM (Applied Psychophysiology and Biofeedback, 2007)
doi: 10.1007/s10484– 006–9028–0.