Paper by D. R. Jackson and K. L. Williams, Applied Physics Laboratory, University of Washington, Seattle, WA.

Jeongguk Kim and Peter K. Liaw (JOM)

Yoseph Bar-Cohen, Tianji Xue and Shyh-Shiuh Lih (NDTnet)

David A. Stubbs and Rollie E. Dutton, (JOM - a publication of The Minerals, Metals and Materials Society)