1. Bolef, D. I., Melamed, N. T., Menes, M.: J. Phys. Chem. Solids 17 (1960) 143.
2. Jaffe, H., Berlincourt, D., Krueger, H., Shiozawa, L.: Proc. 14th Ann. Conf. Frequency Control (1960), unpublished, cited in [67C3].
3. McSkimmin, H. J., Bateman, T. B., Hutchson, A. R.: J. Acoust. Soc. Am. 33 (1961) 856.
4. Berlincourt D., Jaffe, H., Shiozawa, L. R.: Phys. Rev. 129 (1963) 1009.
5. Corll, J. A.: Phys. Rev. 157 (1967) 623.