Burgess, T, et al. “The Effect of the Contract-Relax-Antagonist-Contract (CRAC) Stretch of Hamstrings on Range of Motion, Sprint and Agility Performance in Moderately Active Males: A Randomised Control Trial”. South African Journal of Sports Medicine, vol. 31, no. 1, Apr. 2019, pp. 1-5, doi:10.17159/2078-516X/2019/v31i1a6091.