Mustafa Aziz YILDIRIM, et al. “Effectiveness of Ultrasound Therapy on Myofascial Pain Syndrome of the Upper Trapezius: Randomized, Single-Blind, Placebo-Controlled Study”. Archives of Rheumatology, vol. 33, no. 4, Dec. 2018, pp. 418-23, doi:10.5606/ArchRheumatol.2018.6538.