1. Mason W. P. 1950 Piezoelectric Crystals and Their Application in Ultrasonics
2. Techniques and equipment for fatigue testing at very high frequencies;Neppiras;Proc. ASTM,1959
3. Eisner E. Seager J. S. 1963 Safety in Mines Research Establishment,
4. Eisner E. 1964 J. Acoust. Soc. Am. 36
5. Mason W. P. Wick R. F. 1951 J. Acoust. Soc. Am. 23