Sotomayor, J., and M. Ramírez. “Wave Speed and Modulus of Elasticity by Ultrasound and Stress Waves of Pinus Spp. Mexican Wood Beams”. Revista Ingeniería De Construcción, vol. 30, no. 1, Apr. 2015, pp. 69-79, doi:10.4067/S0718-50732015000100006.