1. J.M. Milne and W.N. Reynolds, Proceedings of the SPIE vol 590, 293–297, 1985.
2. W.N. Reynolds, Canadian Journal of Physics vol 64 (9) 1150–1154, 1986.
3. R.L. Smith, VTT Symposium 93 Proceedings of Anglo-Finnish Joint Symposium on Advances in Nondestructive Testing, 26–32, 1988.
4. C. Hobbs, D. Kenway-Jackson and J.M. Milne, Proceedings of the SPIE vol 1467, 264–277, 1991.
5. C. Hobbs, Sensor Review vol 12 (1), 8–13, 1992.