1. Lehmann JF, DeLateur BJ. Therapeutic heat. In: Lehmann JF, editor. Therapeutic heat and cold. 4th ed. Baltimore: Williams & Wilkins; 1990. p. 448.
2. Electromagnetic Radiation. Britannica Web site. http://www.britannica.com/EBchecked/topic/183228/electromagnetic-radiation . Accessed 18 June 2012.
3. Robertson VJ, Ward AR, Jung P. The effect of heat on tissue extensibility: a comparison of deep and superficial heating. Arch Phys Med Rehabil. 2005;86(4):819–25.
4. Draper et al. Hot packs and 1-MHz ultrasound treatments have an additive effect on muscle temperature increase. J Athl Train. 1998; 33(1):21–4.
5. Cetin et al. Comparing hot pack, short-wave diathermy, ultrasound, and TENS on isokinetic strength, pain, and functional status of women with osteoarthritic knees: a single-blind, randomized, controlled trial. Am J Phys Med Rehab. 2008;87(6):443–51.