Choi J, Lee Y, Lee DY, Yu JH, Kim JS, Kim SG, Hong J.  Immediate Effects of Foam Rolling and Proprioceptive Neuromuscular Facilitation Stretching on Hamstring Flexibility.  J Kor Phys Ther 2022;34:116-120.  https://doi.org/10.18857/jkpt.2022.34.3.116