IEEE Transactions on Ultrasonics Ferroelectrics & Frequency Control. Mar99, Vol. 46 Issue 2, p366. 6p. 5 Black and White Photographs, 2 Charts, 2 Graphs.
IEEE Transactions on Ultrasonics Ferroelectrics & Frequency Control. May98, Vol. 45 Issue 3, p728. 11p. 4 Black and White Photographs, 2 Diagrams, 9 Graphs.