Erfanifam, S., Zherlitsyn, S., Yasin, S., Skourski, Y., Wosnitza, J., Zvyagin, A., et al. (2014). Ultrasonic investigations of the spin ices Dy2Ti2O7 and Ho2Ti2O7 in and out of equilibrium. Physical Review B, 90(6): 064409. doi:10.1103/PhysRevB.90.064409.