Smeaton, M. D., R. C. Hughes, J. Vrba, and R. R. Haering. 1976. “Nanosecond Acoustic Strain Pulses from CdS Phonon Masers”. Canadian Acoustics 4 (2):30-35. https://jcaa.caa-aca.ca/index.php/jcaa/article/view/390.