Poh Thean, C.A. , Awang , M.S. and Athar, S.S.H. 2018. Comparison between High Frequency and Low Frequency Portable Transcutaneous Electrical Nerve Stimulation in Patients with Knee Osteoarthritis: A prospective Randomized Study. IIUM Medical Journal Malaysia. 17, 1 (Dec. 2018). DOI:https://doi.org/10.31436/imjm.v17i1.832.