Bohannon, R.W., Wang, Y.-C., & Gershon, R.C.  (2015). Two-Minute Walk Test Performance by Adults 18 to 85 Years: Normative Values, Reliability, And responsiveness. Archives of Physical Medicine and Rehabilitation, 96(3), 472-477. https://doi.org/10.1016/j.apmr.2014.10.006